Unveiling the Cosmic Mysteries of Bryn Celli Ddd: Explore the Celestial Secrets of the Neolithic Solstice Sun
- apeach5
- Apr 4
- 30 min read
Updated: Apr 22
Introduction
Beneath a sky stitched with timeless tales, Bryn Celli Ddu rises—a sacred mound on Wales’ windswept Isle of Anglesey, still touched by the eternal pulse of the cosmos. For millennia, this place has drawn seekers: Mesolithic wanderers, Neolithic builders, Bronze and Iron Age dwellers, and today’s pilgrims—pagans and poets alike. They come to stand within the Mound in the Dark Hazel Grove, to feel the breath of ancient winds and hear the faint hum of sanctity still lingering in its stones.
But what still calls them here?
Imagine a realm where light dances with shadow, where stone lifts its face to the heavens, and where the ancients forged a silent pact with the universe. In this last chapter of our journey, we step into the heart of Bryn Celli Ddu’s celestial embrace, tracing the astronomical alignments that tether its henge, stone circle, passage tomb, and solitary stones to the eternal cycles above. Each midsummer, the sun’s first rays pierce the tomb’s narrow corridor to flood the chamber with gold, a fleeting resurrection of the ancestors’ memory etched into earth and rock. This is no mere monument, but a bridge between worlds, where the living aligned with the stars to honor the dead.
This essay unwinds the threads of mystery woven into Bryn Celli Ddu, where the interplay of sun and stone reveals a sacred dialogue with the sky. Its celestial gaze joins a chorus of ancient wonders—Giza’s pyramids, Karnak’s temples, the Inca’s Intihuatana—where humanity too sought the secrets of the stars.
Back on Anglesey, we explore the site’s standing stones marking sunrises and sets, quiet memories of possible lost circles, hinting at forgotten rites, their alignments whispering of a bond between soil and ether. Through light, sound, and spirit, the past speaks—not in echoes, but in a sensory hymn that pulls us into a world where the divine and mortal once met. Prepare to roam a landscape where stones whisper, light sings, and the cosmos still beckons.
Heaven’s Light, Earth’s Temple
At Bryn Celli Ddu the midsummer sun weaves its golden beams through the tomb’s ancient corridor into the sacred centre, unveiling a secret, silent, language of the stars. This is no random gift of dawn: the passage’s precise tilt captures the solstice sunrise, a testament to Neolithic hands that sculpted earth to mirror heaven. Within this hollowed sanctum, light does more than illuminate, shifting with the rhythms of a cosmos the builders knew intimately. What secrets did they glean from the sky? What truths did they carve into these stones?
For many, the tomb’s walls, weathered witnesses to long lost rituals, are imbued with an intangible energy that once bridged the mortal and the divine. Here, across the threshold and into the tomb, the interplay of light and shadow becomes a living rite—a solar embrace that bathes the chamber, perhaps to renew the spirits of the departed or to align the living with forces beyond the veil. Beyond the tomb, the henge and scattered stones may have perhaps marked other celestial moments—winter solstices, equinoxes, perhaps even the rise of bright stars like Sirius—each a note in an astronomical symphony played across millennia. Certainly, Bryn Celli Ddu’s alignment differs from its sister sites like Maeshowe and Newgrange that honour the winter solstice sun. This shift to summer light may echo the earlier henge’s orientation, a legacy too sacred to erase, as Hemp (1932) suggests with evidence of a later passage extension, too precious to be forgotten at the religious reformation that transformed the site from open henge to closed tomb.
Bryn Celli Ddu is not alone in this stella ambition. Across continents, ancient minds turned skyward: Giza’s pyramids framed the Orion constellation, Karnak’s temples tracked the sun’s arc, Angkor Wat was later set up to encode the solstices and equinoxes into its immortal design, and Machu Picchu’s Intihuatana stone bound the Inca to solar cycles. Like them, Bryn Celli Ddu’s builders wove their sacred spaces into the fabric of the universe, crafting not just tombs or temples, but portals to eternity. On Anglesey, the solitary stones—remnants of a once-vast circle—stand as silent poets, their alignments a fragile thread to a time when humanity was still in step with the cosmos.
Across the globe, ancient stones rise to greet the heavens, their alignments lacing a celestial bond through time. At the Great Pyramids of Giza, precise edges honed to the cardinal points and shafts perhaps tracing starry paths—like Sirius or even more speculatively Orion’s Belt—forge a timeless link between pharaohs and the divine, a legacy spanning millennia. The Great Sphinx, its leonine form gazing eternally eastward, is thought by some researchers to align with the vernal equinox sunrise millennia before its current dating, reinforcing its role as a guardian of cosmic order, though this remains a subject of much contentious debate.
I have written in some detail about the calendrical orientations at sacred sites here,
These examples, though scattered across the globe, speak to a shared human understanding—that the sun, the stars, and the rhythms of the universe are not mere phenomena to be observed, but forces to be understood and aligned with. As these ancient civilisations looked to the skies, they built their sacred sites not just to honor the gods, but to create a cosmic harmony between the celestial and the earthly.
It is with this broader context in mind that we now turn our focus back to Bryn Celli Ddu. In part 4 of our deep dive. Here, too, the alignment of the tomb speaks a language of transformation, a communion between the living and the divine that echoes across the ages, offering us a glimpse into the profound relationship between humanity and the heavens.
Bryn Celli Ddu: The Ancient Bond Between Sky, Stars and the Earth
Bryn Celli Ddu has long intrigued researchers with its major astronomical alignment. One of the earliest to investigate this was Sir Norman Lockyer in 1906. Based on his observations, Lockyer hypothesised that the tomb's passage was aligned to capture the sunrise during the summer solstice. However, his contemporaries met this claim with skepticism, and it did not gain widespread acceptance at the time.
Interest in Lockyer's theory resurfaced in the early 21st century when archaeologist Dr. Steve Burrow revisited the site. Inspired by Lockyer's original work, Burrow conducted observations in 2005 and confirmed that at dawn on the summer solstice, sunlight penetrates the passageway, illuminating the inner chamber precisely as Lockyer had proposed. He noted that the light penetrated the tomb and illuminated the rear wall with a "well defined yellow box" before narrowing to a thin strip of light over 30 minutes. He also described the illuminated stone as having "chunks of quartz which, if the stone was clean, might reflect the light". Burrow goes on to suggest that one of the original stones (H) of the destroyed circle was used in conjunction with the central foundation pit in order to make sure the tomb's passageway was wide enough to encompass the rising solstice sun from within the central chamber of the new monument". Further more, "lines marked out from (stones) 'G' and 'I' across the central pit are mirrored in the alignment of two orthostats in the tomb chamber". This evidence suggests the orientation to the summer solstice sunrise was deliberately carried over from the original older monument to the new tomb. This alignment was tightened in a later modification of the tomb "in order to increase its drama" (Burrow, 2010, pp. 258-264).
From Frances Lynch (1973) proposed that the outer passage of Bryn Celli Ddu may have been deliberately blocked during the Neolithic, sealing the dead off from the living. Drawing on evidence from Hemp’s earlier report, she suggested that this blocking allowed only a narrow slit for sunlight to penetrate the chamber similer to the roof boxes found at Newgrange and Cairn G, Carrowkeel both in Ireland. If this were the case at Bryn Celli Ddu, any later additions of human remains would have required either pushing or throwing them in or removing the clay-set packing to gain access.
The possibility that the chamber was sealed at an early stage raises questions about how the dead were conceptualised within the tomb. Lynch noted that the presence of the free-standing stone pillar on the north side of the chamber is significant. Aubrey Burl (1999, p167) interpreted this stone as a ‘protectress,’ (feminising a phallic stone) and drawing comparisons with similar stones found in Breton tombs and with the anthropomorphic decoration on stone 22 at Barclodiad y Gawres, another Anglesey monument (there are also similar stones in large tombs in Spain and Portugal). Within the chamber’s dim interior, the pillar appears to take on a human-like form. Significantly, the pillar stands in a part of the tomb that remains in permanent shadow. If understood as a guardian figure, it has silently watched over the human remains in the chamber since their deposition, bearing witness to the solstice sunrise as it illuminates the quartz-rich rear wall—while never itself being touched by the light.
If Lynch’s interpretation is correct and the outer passage was sealed soon after construction, then for much of the tomb’s history, the pillar may have been the only ‘witness’ to the solar event, at least until the site was disturbed in later periods. This perspective alters the meaning of the solstice alignment, suggesting that it was designed primarily to address the dead rather than to serve a ritual function for the living.
This alignment places Bryn Celli Ddu among a select group of Neolithic sites designed with astronomical considerations. Similar alignments are observed at Maes Howe in Orkney and Newgrange in Ireland, though these are oriented towards the midwinter solstice sunrise as already noted. Stonehenge famously orientates on the solstice line commemorating midsummer sunrise as well as midwinter sunset. The midwinter sunset is also built into Bryn Celli Ddu as we shall see when looking at the standing stones. I have proposed elsewhere that the solstice line itself—stretching from dawn to dusk like a taut string across the year—was the sacred chord, its terminals mere notes in a greater harmony.
As already explored, the original orientation was probably inherited by the tomb from the original henge and stone circle. Hemp argued that the construction phases of Bryn Celli Ddu suggested the later passage may have been extended during a second phase to enhance the visual impact of the solstice sunrise. This modification indicates a deliberate effort by its builders to commemorate the older monument by framing the solar event more precisely, underscoring the cultural significance and continuity of such celestial occurrences in Neolithic societies. (Hemp, 1932)
The solstice alignment at Bryn Celli Ddu exemplifies the sophisticated understanding of astronomy possessed by Neolithic builders. It also highlights the broader cultural practice of integrating architectural structures with celestial events, a phenomenon observed at various prehistoric sites across Europe.
Other stones at Bryn Celli Ddu have important astronomical alignments too and it is to these that we now turn.
The Stones Stand Silent: An Introduction to the Menhirs of Europe and Beyond
Standing stones, also known in Europe as menhirs, are among the most iconic and enigmatic monuments of the prehistoric world. They are found across a vast geographical range, from the British Isles and Brittany to Scandinavia, Iberia, and the Mediterranean, as well as parts of North Africa and the Near East. Their distribution suggests independent developments as well as cultural diffusion, with notable concentrations in regions like Scotland, Ireland, and France, where they often appear in alignments, circles, or solitary forms. Their construction spans a broad period from the late Mesolithic through the Neolithic and into the Bronze Age (circa 7000–3000 B.P.), though precise dating often relies on associated archaeological contexts.
In terms of placement, standing stones are frequently found within or near complex ceremonial landscapes, including henges, passage graves, stone circles, and cursus monuments.
The purpose of standing stones remains a subject of considerable debate. Hypotheses range from their function as territorial markers or commemorative monuments to their use in religious and ritual activities. Increasingly, researchers have noted their alignment with celestial events, such as solstices, equinoxes, and lunar cycles, signaling a sophisticated understanding of astronomy among prehistoric peoples. Alignments with distant monuments, landscape features, or bodies of water further underscore their significance within a broader cosmological framework.
Some scholars, like Professor Terrance Meaden, have proposed that the standing stones may possess symbolic, statuesque elements, perceived through pareidolia, the phenomenon where the human brain identifies patterns such as faces or animals in random or ambiguous forms, such as stones, clouds, or even hills and mountain ranges. Meaden's theory suggests that these stones, much like natural formations, may have been intentionally shaped or selected for their resemblance to human or animal figures, evoking deeper meaning through their very form. Meanwhile, Andrew Keiller, the renowned archaeologist and restorer of Avebury, advanced a provocative interpretation of the stone monuments at the iconic site. Keiller suggested that the stones at Avebury could symbolise fertility and sexuality, with phallic shapes representing male potency and diamond-like formations representing the feminine. These ideas, though controversial, reflect the broader, symbolic interpretation of standing stones and other megalithic structures across ancient Britain and beyond.
Both theories open up a fascinating discussion about the ways in which humans have historically imprinted their symbols and meanings onto the natural world, and how such interpretations might have influenced the construction of megalithic monuments. This notion of stones as bearers of symbolic, sexual, or anthropomorphic representations continues to intrigue, and I look forward to delving deeper into this topic in a future post.
The Stones that Gaze: Marking the Dreaming Skies
As research unfolds, the greater ritual landscape surrounding Bryn Celli Ddu gradually emerges from the fog of time. Through the groundbreaking geophysical surveys conducted by Dr. Mike Woods, the hidden features of this site are being brought to light—unearthing forgotten features of the past, including the remnants of what may have once been stone circles destroyed as part of a past religious reformation. Dr Woods believes this may be more common than had been previously thought. I hope to join him soon to investigate a possible lost circle. Today, the lost circles are but echoes in the earth, their previous grandeur reduced to solitary standing stones, their ancient companions lost to the ravages of the past. A recent excavation in Derbyshire has revealed another such circle, with only a single stone remaining to mark its once-proud presence.
Dr. Woods suggests that these solitary stones may serve as markers commemorating the lost circles that once stood tall and proud. Perhaps they are the deliberate work of religious reformers, who left behind these singular monuments as a testament to the past—both as remembrance and as a symbolic gesture born of reverence, or perhaps even fear, of the lingering power of the Old Gods. The haunting presence of these stones, forsaken yet enduring, may speak of an ancient desire to preserve the old ways, even as they were cast aside in the face of new spiritual beginnings. A question arises, why was that particular stone chosen to survive? Was it an important stone within a circle? Or just a random choice.? The standing stones of Bryn Chelli Ddu might offer a clue.
The Standing Stones of Bryn Celli Ddu: Alignments, Astronomy, and a Deeper Mystery
At Bryn Celli Ddu, two standing stones remain at the site, their silent presence evoking a connection to something greater. Both are aligned with celestial events, one perhaps the survivor of a lost circle, marking a subtle yet profound connection between earth and sky and the possible reason for its choice to survive. These stones, like their counterparts across the world, are not mere markers of land; they are part of a larger living system, guiding the people not only through the physical ritual space but also across the rhythms of the cosmos itself. The very placement of these stones seems to speak of a time when the sky above was as sacred as the earth below, and the boundaries between the two were conjoined, ever intertwined in the rituals and beliefs of those who built them. Building upon the general understanding of standing stones, the two notable examples at Bryn Celli Ddu—the southwest stone, with its distinctive rounded shape, and the northwest stone, linked to key celestial events—reveal an intricate interplay of astronomy, ritual, and Neolithic landscape design. These stones do not merely stand as isolated markers; rather, they appear to interact with the tomb itself and with the movements of the sun and moon, reinforcing the site’s importance as a place of profound cosmological significance.
The Southwest Stone and the Solstice Sunrise
The closest stone is 137 metres to the southwest of Bryn Celli Ddu, in the neighbouring field to Bryn Celli Ddu Bach and stands just over one metre in height. The southwest standing stone serves as a crucial vantage point from which the summer solstice sunrise can be observed rising above the tomb. This alignment is particularly striking when considered alongside the passage tomb’s orientation, where the first rays of the midsummer sun penetrate its narrow corridor, illuminating the inner chamber. The fact that both the passage and the standing stone frame the same celestial event suggests an intentional design that ties the site to the rhythms of the year (Burrow, 2010; Heath & Heath, 2011).
Furthermore, the shape of the southwest stone—wider than it is tall, with an almost circular form—may carry deeper symbolic meaning. Such a rounded form could represent the solar disc itself, reinforcing the connection between the monument and the annual rebirth of the sun. As the dawn light spills over the horizon, the stone becomes part of a living drama of shadow and illumination, a moment of transformation embedded in the landscape (Sims, 2006). The stone is also raised on an area of lowland in comparison to the immediate surroundings (standing stones are often raised in upland areas, although the distribution on Anglesey strongly indicates that this is not the case on the island). It also exhibits an unusual, drilled hole on the top. Dr Woods points out there are other stones in Anglesey with this feature. (Woods, 2021). There is a debate whether these are original or modern features. If original, could this have been the setting for a wooden marker or some other sort of decoration of shadow maker/marker connected to the sunrise?
Tyddyn Bach: The Northwest Stone and the Dance of Sun and Moon
While the southwest stone marks the peak of the solar year, the northwest stone plays a more enigmatic role, engaging with both the sun and moon over long cycles of time. This is a named stone. Tyddyn Bach (the Small House). 3.3 meters tall and 450 metres northwest of the tomb. This stone contrasts with the other by tapering to a point towards the top and the base of the stone is surrounded by a large clearance cairn. Located on a valley slope with good views of both Bryn Celli Ddu, as well as the Snowdonia Mountain Range on the horizon, this stone has intriguing astronomical alignments.
Tyddyn Bach has been linked to both the major lunar standstill and the winter solstice sunset (Heath & Heath, 2011). The stone aligns with the setting sun on the year’s shortest day—marking the symbolic death and rebirth of light. Moreover, the tomb itself lies on the opposite terminus of the solstice line, suggesting an interconnectedness between the burial mound, the stone, and the turning of the seasons.
Even more remarkably, the northwest stone also aligns with the extreme position of the moon during its 18.6-year cycle, indicating that the Neolithic builders possessed a sophisticated understanding of both solar and lunar movements. This dual function—tying together the rhythms of the sun and the longer, more elusive cycles of the moon—highlights the importance of celestial events in Neolithic timekeeping and ritual practices. Similar alignments have been observed elsewhere, including at Stonehenge, the chambered tomb of Maeshowe in Scotland, Gavrinis in France, Callanish and other monuments on the Isle of Lewis and various other Scottish sites such as the recumbent stone circles of Aberdeenshire (Burrow, 2010; Sims, 2006; Heath & Heath, 2011).
A May Day Connection?
While examining the solstice alignments at Bryn Celli Ddu, I came across a paper by Sparavigna (2017) that tested the possibility of a May Day sunrise alignment with the tomb’s entrance. The study found no such alignment, but the accompanying map intriguingly revealed that the May Day sunset fell to the northwest—in the direction of the northwest standing stone. With some tricky calculations, I found that if one stood at the centre of Bryn Celli Ddu around 4500 B.P., the sun would have set in alignment with the northwest stone on May Day. In prehistoric times, May Day, aligned with the Celtic festival of Beltane—likely held deep significance as it marked the transition from spring to summer, a time when the earth’s fertility surged, and communities celebrated renewal, growth, and the strengthening sun. For agrarian societies, this date, falling around May 1st, would have been a key moment to honor the cycles of nature, ensure bountiful harvests, and perform rituals to appease deities or spirits believed to govern life and abundance.
Coincidence? Probably. My calculations could be wrong, and I welcome those with the expertise to check them. But if correct, this would suggest that the site's astronomical sophistication is even greater than currently understood, warranting further research.
Unfinished Mysteries and the Promise of Discovery
Bryn Celli Ddu continues to communicate its enigmas across the ages, its stones casting long shadows over time itself. Whether by accident or ancient intent, these megaliths stand in silent communion with the heavens, marking the endless cycles of light and darkness, life and death. They are the bones of the land and the memory of the sky, waiting for the right moment—or the right observer—to reveal their truths. Dr Wood’s ongoing research holds promises of new discoveries. Watch this space.
Now it is time to move onto some of the more esoteric findings at Bryn Celli Ddu, namely the puzzles and speculations surrounding sound and light phenomena at this site. Firstly, the stone age soundtrack of the past.
The Acoustic Properties of Standing Stones in Prehistoric Landscapes
The acoustic properties of standing stones have been the subject of increasing interest in archaeological and archaeoacoustic research. Various studies suggest that these megalithic structures may have played a significant role in amplifying, reflecting, and directing sound, potentially influencing rituals involving music, chanting, or other auditory elements.
Examples of Acoustic Effects in Megalithic Sites
Stonehenge
Research by Rupert Till and Bruno Fazenda (2020) has shown that Stonehenge’s sarsen circle creates a unique acoustic environment, with the stones reflecting and reinforcing sound waves within the enclosed space. Computer models and physical experiments suggest that this effect would have made chanting or percussive sounds more immersive, potentially enhancing communal ceremonies.
Carnac, France
The Carnac alignments, with their thousands of standing stones, present another potential case for acoustic manipulation. Paul Devereux (2001) has suggested that the narrow corridors formed by some of these stones could act as resonant pathways for sound, amplifying the effect of drumming or chanting. Experimental work has also shown that some stones produce distinct percussive tones when struck, leading to speculation that they may have functioned as lithophones (ringing stones).
The acoustic properties of standing stones suggest that sound was an integral part of prehistoric ritual spaces. Whether through amplification, resonance, or psychoacoustic effects, these stones may have played a key role in ceremonies, music, and communication. While more experimental work is needed, the growing field of archaeoacoustics continues to uncover fascinating insights into how Neolithic and Bronze Age societies interacted with their environments through sound. Rupert Till and Bruno Fazenda’s Work on Megalithic Acoustics (2010, 2020) has examined how enclosed or semi-enclosed stone structures can enhance low-frequency sounds, potentially evoking altered states of consciousness.
Light, Sound, and Sensory Effects: A Prehistoric Society of Spectacle?
The Solstice Sunrise at Bryn Celli Ddu
Light played a fundamental role in prehistoric Europe, shaping the design and significance of many ancient monuments. Across Neolithic and Bronze Age landscapes, structures were deliberately aligned with celestial events, harnessing sunlight, moonlight, fire, and reflective materials to create powerful visual effects. These interactions with light were not incidental; rather, they were integral to the way people experienced and understood their monuments, linking them to seasonal cycles, agricultural rhythms, and possibly spiritual beliefs.
One of the most striking examples is Newgrange in Ireland, where, during the winter solstice, a shaft of sunlight enters through a specially constructed roof box, illuminating the tomb’s inner chamber. Similar solar alignments can be found at Maeshowe in Orkney, where the setting sun at midwinter shines directly down the passage, and at Stonehenge, where the summer solstice sun rises in alignment with the monument’s entrance and the Heel Stone. Other sites, such as Loughcrew in Ireland, display equinox alignments, where sunlight briefly illuminates intricate carvings deep within the tomb.
Beyond the sun, the moon also played a role in prehistoric light effects. At Callanish in Scotland, every 18.6 years, the major lunar standstill creates a dramatic visual event, with the moon appearing to skim low along the horizon, almost touching the stones before disappearing behind distant hills. I have written about this phenomenon here.
Artificial light also transformed prehistoric spaces. The flickering of torchlight in darkened tombs and caves could have animated carvings, casting shifting shadows that gave the impression of movement. Fire may have played a ritualistic role, illuminating burial chambers or being used as a symbolic tool in ceremonies. The presence of charred remains in monuments hints at the controlled use of fire, possibly as part of funerary rites. I have written in some detail on these effects here.
Materials used in structures could enhance light effects. Quartz, a highly reflective mineral, was often incorporated into Neolithic structures, such as Gavrinis and Newgrange, where its glistening surface would have caught and scattered light. Polished stone, too, could have been used for its reflective properties, while still pools of water might have functioned as natural mirrors – as I speculate at Gavrinis - reflecting the light from the moon into the heart of the tomb.
Camera Obscura: A Spectacle in the Temple?
The study of light within Neolithic passage tombs has revealed some remarkable optical effects, reshaping our understanding of how these monuments were experienced. Recent research into archaeo-optics, the study of light and vision in past societies—has demonstrated that passage graves, with their narrow entrances and enclosed chambers, naturally reproduce the principles of a camera obscura. This phenomenon allows for striking visual projections, including beams of light, glowing orbs, and inverted and reversed images of the external world or hands, figures and any other object appearing on the chamber walls.
Dr. Aaron Watson's research into archaeo-optics suggests that certain Neolithic passage tombs may have functioned as primitive camera obscuras, where light entering through the passage or small apertures projected images onto the interior surfaces. Watson and his collaborator Dr. Ronnie Scott have explored how these projections could have been an intentional aspect of the tombs’ design, potentially linked to ritual experiences, cosmological beliefs, or sensory manipulation within the monuments (Watson & Scott, 2016).
Their studies indicate that the long, narrow passages of Neolithic tombs, combined with the controlled entry of light, could create shifting images or patterns inside the chambers, particularly during key astronomical events such as solstices and lunar standstills. This effect might have contributed to an otherworldly or transformative experience for those within, reinforcing the tombs' significance as liminal spaces between life and death (Watson, 2016).
Drawing from experimental archaeology, Watson has also demonstrated how simple modifications to passage shapes or openings could enhance the optical effects, suggesting that Neolithic builders may have had an intuitive, if not fully scientific, understanding of light projection. His findings align with broader discussions on the sensory experience of prehistoric monuments, where elements like sound, darkness, and movement interact to create immersive ritual environments.
Experiments conducted at Bryn Celli Ddu have led to Dr Watson has confirming that during midsummer sunrise, sunlight entering the passage can produce an enlarged, projected image of the sun’s disc within the chamber. Such effects could have been further enhanced by the deliberate use of apertures—perhaps created with materials like animal hide screens—to refine and focus on the projected imagery. These possible projections, combined with the monument’s potential acoustic properties and its alignment to celestial events, suggest that the sensory experience within the tomb could have been profound.
While modern science explains these effects through optical physics, if Neolithic people used them, they would have understood them through their own cultural frameworks as a probable mysterious and magical phenomenon, interpreting passage graves as spaces where the boundaries between life and death were negotiated and communion could be reached. Could these vivid, otherworldly light effects have reinforced such beliefs? Were they seen as manifestations of the divine or as portals to an unseen realm?
The possible presence of these carefully designed light effects suggests that prehistoric people viewed light as more than just a source of illumination—it was a bridge between worlds, a marker of time, and a tool for shaping sacred spaces. At Bryn Celli Ddu, where the monument’s passage aligns with the rising midsummer sun, this interplay of light and structure invites questions about how the Neolithic builders perceived their world. Was the illumination of the chamber a symbolic act, representing rebirth or the return of ancestral spirits? Did the site’s placement within the blueschist belt and near the River Braint reinforce a sacred geography, where light, stone, and water converged?
Whatever the precise intentions of its builders, the possible use of light at Bryn Celli Ddu echoes a broader prehistoric tradition—one in which light was carefully manipulated to shape human experience, reinforce cosmic connections, and inscribe meaning into the landscape.
Acoustics – echoes, resonance, and their potential ritual significance.
Archaeoacoustics is the study of sound in archaeological contexts, exploring how ancient cultures may have intentionally utilised acoustics in their structures and landscapes. This field examines how sound could influence human perception, ritualistic practices, and even states of consciousness.
The Speaking Stones
The connection between rock art and echoes has emerged as a compelling area of study in archaeoacoustics, suggesting that prehistoric people may have deliberately sited their artistic expressions in locations with distinct acoustic properties. Echoes, produced by sound reflecting off rock surfaces, could have enhanced the sensory experience of these sites, potentially imbuing them with ritual or symbolic significance. Research indicates that many rock art locations, such as caves or cliffs, exhibit pronounced acoustic effects, hinting at an intentional interplay between visual and auditory phenomena in ancient cultural practices (Devereux, 2001). Link Here
At Bryn Celli Ddu, researchers Paul Devereux and George Nash have investigated the site's acoustic properties. In their 2014 study here, they reported that percussive sounds made while standing at Bryn Celli Ddu echoed noticeably from the northwestern rocky outcrop approximately 140 meters from the tomb. This outcrop features prehistoric art as already discussed in part 3. The researchers proposed that these echoes might have been perceived by ancient peoples as the voices of spirits or ancestors responding from within the stone, with the cup marks potentially serving as markers of these sacred acoustic spots. Again, the question is, is the siting of the monuments here influenced by the western outcrop which is increasingly demonstrating unique properties? As an aside, Dr Mike Wood has also told me he has evidence suggesting that some cup-marked stones in the area function as lithophones (rock gongs) further underlining the sensory environment of the past in this area. (Private message). I speculate in part 3 on the importance of the large rock outcrop to the northwest as a probable sacred landscape feature that first sanctified the site and led to its monumental commemoration across millennia. See here.
Steve Marshall’s studies of chambered tombs in Southern England, such as West Kennet Long Barrow, suggest that their design intentionally harnessed sound, producing resonances that may have shaped ritual experiences (Marshall, 2016).
His work on the West Kennet Long Barrow revealed that its chambers resonate at specific frequencies, creating harmonic intervals such as the ‘perfect fourth’ that enhance sounds. This is linked to the proportion of the chambers’ construction being built in a 4:3 ratio. Marshall also showed that the tomb’s passage produces infrasound—low-frequency vibrations capable of influencing human consciousness. These effects suggest that sound plays an integral role in ritual experiences within such spaces.
While Bryn Celli Ddu has not been extensively tested for similar resonances (not least because it is only partially reconstructed and open at the back), its architectural similarities to other passage graves imply the potential for comparable effects. Marshall’s findings support the idea that Neolithic and Bronze Age societies engaged with sound as a sensory and symbolic medium, reinforcing the likelihood that sites like Bryn Celli Ddu were used for immersive, acoustically enhanced ceremonies.
Similar acoustic properties have been documented at the prehistoric temple of Ħal Saflieni Hypogeum in Malta, where its chambers resonate at frequencies between 94Hz and 103Hz. These low-frequency sounds can induce physiological responses in listeners, potentially leading to altered states of consciousness during rituals (Till, 2017).
Although Bryn Celli Ddu has not yet been rigorously tested for resonance frequencies, its architectural kinship with other passage graves strongly suggests that it, too, may have been designed with acoustics in mind. The deliberate design of such spaces to enhance sound effects implies a sophisticated understanding of acoustics by their builders, possibly to facilitate spiritual or shamanistic experiences.
Returning to the subject of lithophones, one peculiar experience at Bryn Celli Ddu still lingers in my memory. While testing the tomb’s acoustics 25 years ago, my wife and I decided to tap the internal standing stone with the wooden baton I had been using to activate a Tibetan singing bowl I had been experimenting with. To our astonishment, the stone responded—not with a dead thud, as one might expect, but with a low, resonant tone. While lithophonic stones are well known in archeology, we were unprepared for this reverberant moment. Stranger still, when we returned some years later and attempted to replicate the sound using the palm of our hands, we found the stone silent. Perhaps it was the baton, or the precise angle of the strike, or something more elusive, something momentary, irretrievable, as if the stone had chosen that singular moment to speak. I documented this experience as a personal anecdote on the “Modern Antiquarian” website under the fieldnotes section of the site. Make of it what you will, but if it did not happen and we somehow were mistaken, the fact the two of us remember it clearly is remarkable in itself. But mind and memory can play tricks, and perhaps the tomb affected my consciousness somehow that day.
See the field notes section on Bryn Celli Ddu under my rock and roll stage name pseudonym Porkbeast here.
The topic of prehistoric sound and its effects on consciousness is an intriguing one, and I intend to write an in-depth article on this subject in the future. This brief exploration of Bryn Celli Ddu’s acoustic potential is just the beginning. Future research may reveal even more about how Neolithic builders shaped not only stone but sound itself, creating environments that engaged the senses in ways we are only beginning to understand.
In summary, the interplay of acoustics and architecture at Bryn Celli Ddu suggests that Neolithic people intentionally designed their sacred spaces to harness both sound and light. The echoes from the cup marked outcrop and the potential resonance within the tomb's chamber could have been integral to rituals, serving to connect participants with the spiritual realm. These multisensory experiences, combining acoustic effects with
observed light phenomena, likely played a crucial role in the ceremonial and cultural practices of the time.
Addendum.
Heather Rendall made this comment about another acoustic property of a standing stone in Anglesey.
“I used to live at Star at the top of the hill above the A5 between Llanfair PG and Gaerwen.
Two doors down along me on the top of the hill used to stand The Whispering Stone. Apparently before it was laid down’, if one stood by it and spoke in a low voice, one could be heard in the hollow down the hill now occupied by the council houses.”
There are also modern artists experimenting with light and sound at Bryn Celli Ddu. See below.
From Stars to Settlement: Bryn Celli Ddu’s Enduring Legacy
As the Neolithic voices of Bryn Celli Ddu fade into the earth—its solstice sunbeams and lunar light captured in stone—the site’s story does not end. Across the centuries, its sacred mound and standing sentinels continued to call, their celestial alignments a thread that wove through time. By the Iron Age, this ancient landscape was no longer just a memory of the past; it became a living stage for new inhabitants, their lives etched into the soil atop the bones of their ancestors. Dr. Mike Woods’ geophysical surveys reveal the ghostly outlines of an Iron Age settlement here, a whisper of roundhouses and hearths that suggest Bryn Celli Ddu was not abandoned but re imagined—its cosmic pulse still beating beneath a shifting world.
Anglesey’s Iron Age unfolds in subtle traces: pottery sherds, weathered earthworks, and the stubborn endurance of stone-built homes atop coastal cliffs and hilltops like Holyhead Mountain and Mynydd Llwydiarth. Unlike the towering hillforts of southern Britain, this is a quieter tale of resilience, where place names—Hendrefor, Bryn Eryr—carry the Celtic tongue’s echoes into the present. Dr. Woods’ findings at Bryn Celli Ddu hint at a community of scale, its structures awaiting the spade’s revelation. Did these settlers, like their Neolithic kin, gaze at the tomb’s passage and see a celestial legacy? Did the standing stones, still piercing the sky, guide their own rituals under a sun that had not ceased to mark the seasons?
Historians paint Iron Age North Wales as a time of flux—beliefs bending, economies turning from bronze to fields and flocks, trade webs stretching to distant shores. Finds at Llanfaes and Llandudno gleam with Gaulish gold, proof that Anglesey was no backwater. At Glan Gors, a fortified enclosure challenges old assumptions of tribal simplicity, hinting at a power center yet unclaimed by history. Yet the island’s tale remains half-told, its silence woven from scarce luxury goods and elusive ceramics—only coarse briquetage, tied to the salt trade, peppers sites like Pant y Saer and Bryn Eryr. Burial rites, too, are shadows: a lone warrior at Gelliniog Wen, entombed in a stone cist with a La Tène-scabbarded sword, speaks of European ties and personal honor, but little else.
Bryn Celli Ddu’s Iron Age whispers of continuity and change. Its settlement, perched atop a site already ancient, suggests a reverence for what came before—a landscape too sacred to forsake. The tomb’s alignments, once a bridge to the stars, may have lingered in the settlers’ eyes as a testament to a cosmos still revered, its stones and mound a compass for a people navigating a new age. As excavation looms, we stand on the cusp of a deeper chronicle—one that may unveil how long these walls sheltered life and how far their influence reached.
Conclusion
As twilight cloaks the rolling hills of Anglesey and the stars unfurl their silver map above Bryn Celli Ddu, the strands of this ancient saga converge, threading a tale of wonder that spans millennia. This fourth chapter has swept us into the celestial heart of the site, where the midsummer sun spills golden fire through the passage tomb, igniting its shadowed depths with a radiance that speaks of a profound pact between earth and sky. Here, the builders, those enigmatic architects of the Neolithic, wove their astronomical artistry into stone, aligning their sacred space with the solstice dawn and the moon’s elusive cycles, crafting a sanctuary that pulses with the rhythms of the cosmos. Yet this is but one layer of a narrative that stretches far beyond, a story that binds Bryn Celli Ddu to a global chorus of awe—from the sun-kissed pyramids of Giza to the star-guided Intihuatana of the Andes—where humanity has forever sought to cradle the divine within the turning heavens.
This journey began in parts one and two, where we plunged into the archaeology of the site with a depth unmatched in any journalistic telling, peeling back the layers of time to reveal a tapestry of human endeavor. There, we walked among the echoes of forgotten hands that shaped the mound, unearthed the relics of their lives, and traced the evolution of a place that grew from humble beginnings into a monument of staggering complexity. Part three carried us further into the primal geography that first sanctified this ground, the rugged embrace of the rocky outcrop to the northwest, the sinuous flow of the River Braint, the brooding silhouette of distant mountains, and the rare blueschist geology that shimmered beneath it all. Long before the first wooden monuments of the Mesolithic or the later stones raised in the Neolithic, this landscape spoke of the sacred, its natural majesty drawing reverence that would ripple through the ages, from its earliest monumental stirrings to its modern mantle as Wales’ most cherished ancient treasure.
Now, in this celestial crescendo, the standing stones rise like timeless poets, their solitary forms—once perhaps encircled by lost companions—singing of solstice sunsets and lunar standstills. These megaliths, poised at the edges of the site, are no mere markers; they are conduits, linking the earth to the ether through Apollo’s golden cord—a sacred line bisecting the year’s major solar alignments.
But the wonder deepens yet, as the stones and tombs unveil their hidden voices. The resonant hum of acoustics once stirred the air, while fleeting spectacles of light, built into the passage tomb, were later refined to heighten their drama. These effects may have been further manipulated—perhaps even projected through camera obscura—casting otherworldly visions onto ancient walls. Woven through rituals lost to time, these sensory threads suggest a space where the mortal and the eternal met, where the flicker of torchlight and the echo of a struck stone summoned communion with realms beyond.
Bryn Celli Ddu emerges not as a relic frozen in history, but as a living symphony of light, sound, and spirit—a place where the ancients forged a bridge to the stars and anchored their dreams in the land. From its sacred genesis in the wild geography of prehistory, through the meticulous craft of its Neolithic architects, to the enduring allure that draws countless souls today, it stands as a testament to humanity’s unyielding yearning to touch the infinite. As we turn from its shadowed embrace, the night sky above seems closer, its constellations a mirror to the wonder below. We are left with the indelible sense that here, amid the stones and the silence, the past still breathes, inviting us to join the timeless dance, to feel the pulse of a cosmos that has guided us since the first dawn, and to marvel at our place within its boundless embrace.
Dr Alexander Peach, Siem Reap, March 2025
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Web Resources
Archaeooptics of Bryn Celli Ddu. https://www.aaronwatson.co.uk/archaeooptics-overview
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