Mysterious circles of megaliths (large monumental stones) have intrigued us for millennia. These enigmatic and often elaborate stoneworks are scattered around the British Isles, parts of Europe, Africa and the Middle East. Some were built for ceremonial reasons, others as ancient markers or astronomical instruments, and some for burials or social gatherings. As a new discovery is unearthed in Cornwall, southwest England, we take a look at the mysteries behind these stone structures.

The vast and rich henge monument of Avebury – a complex of Neolithic and Bronze Age ceremonial sites – contains three stone circles, one of which is the largest in all of Europe. Its main outer megalithic circle measures more than 1,000 feet (300m) across and originally consisted of around 100 standing stones. It encloses two smaller circles. The southern circle focused on a central point, the great Obelisk, which was removed in the 18th century. It would have been the largest stone in the circle at 21 foot (6.4m) high.

A circle of vast prehistoric shafts has been discovered just under two miles (3.2km) from Stonehenge. The 20 shafts – more than 33 feet (10m) in diameter and 16.4 feet (5m) deep – seem to have been designed to create a circle around Durrington Walls henge (pictured here) and Woodhenge, another smaller prehistoric circle to the south. Radiocarbon dating revealed the shafts are 4,500 years old and from the Neolithic period. It's likely the same people who constructed Stonehenge built the shafts at Durrington Walls, now the largest prehistoric site discovered to date in the UK.

One of Britain’s most ancient circles, Castlerigg, sits high in the fells of Cumbria – a suitably beguiling setting for such a mystical place. The ring of 38 stones is encircled with the brooding forms of Skiddaw, Blencathra, Castlerigg Fell, High Rigg and Clough Head. It was erected by Neolithic farming communities around 4,500 years ago, possibly as a meeting place.

Go for a ramble on the eastern flank of Black Combe in the southwest corner of the Lake District and you’ll come across the intriguing sight of 55 irregular monolithic stones grouped in a circle. The ancient monument was constructed from local slate and is 93.8 foot (26.8m) in diameter. It’s set on private land but can be admired in all its beauty from the footpath.

Amid the wild and bleak landscape of Burley Moor, part of the larger Rombald’s Moor, lies this intriguing Bronze Age formation. The so-called Twelve Apostles is a series of originally 16 to 20 stones which were likely placed here by ancient farmers. The West Yorkshire moorland, located near Ilkley, also has brooding rock formations, large burial cairns (a mound of stones erected over a burial) and notable Bronze Age rock carvings.

Set within a woodland above the River Nairn near Inverness, the standing stones and burial chambers of Clava Cairns, also known as the Prehistoric Burial Cairns of Bulnuaran of Clava, makes for an enchanting place. The prehistoric cemetery features three well-preserved cairns, each surrounded by a ring of standing stones. It’s thought they date from around 2500 BC and that they were also constructed for astrological purposes, as they are aligned with the midwinter solstice.

The ring-like structure of the Stones of Stenness Circle on the West Mainland of Orkney is even older than Stonehenge. Part of the Heart of Neolithic Orkney World Heritage Site, the 12 tall stones were erected here some time between 3000 and 2500 BC. Sadly only four of the 12 remain in situ but at nearly 20 foot (6m) high they still make a mighty powerful impression.

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Another of Orkney’s archaeological sites, the Ring of Brodgar is an area of great ritual significance and mystery. Also located on Orkney’s largest island West Mainland, the vast circle of towering stones (of which 27 of the original 60 stones remain) were built around 2500 to 2000 BC. According to local legend, it was a religious shrine and place of ritual. Others believe the ring was built for the astronomical observations.

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The granite menhirs (standing stones) of prehistoric site Filitosa, found among the hills and olive trees of the Taravo Valley, are full of mysteries. The oldest date back to 4000 BC, some later carved with human features. One group of menhirs encircles the base of an ancient olive tree. The incredible complex, which includes prehistoric towers and stone houses, was only unearthed in 1948. You can usually find out more about the megalithic site at its insightful museum.

It might be small but this almost perfect circle of ancient stones huddled high in the hills above the Dee Valley is something special. Its remote setting only adds to the palpable sense of history here. The Ring of Tyfos stone circle and Caer Drewyn Hillfort are close by too.

The Peak District National Park is another part of Britain known for its aptly moody landscapes and prehistoric remains (it’s dotted with stone cairns and barrows). The most striking is the Nine Ladies Stone Circle and the King Stone, set 131 feet (40m) away from the circle, in Stanton Moor. There are in fact 10 stones, although one has fallen. Little is known about its purpose but it may well have been a meeting place, or place of ceremony or burial.

This extraordinary ancient site in the countryside of County Cork is full of enigmas. Known by locals as Druid’s Altar, archaeologists discovered an urn burial in the centre of the circle of low stones. Thirteen of the 17 stones remain (one of which is aligned for the winter solstice) and the site has been dated to between 153 BC and AD 127. Remains of a primitive kitchen have also been unearthed.

The brooding moorland in the west of Arran might look desolate but it holds untold secrets of the isle’s fascinating past. The rich archaeological landscape boasts a number of prehistoric monuments including various stone circles, standing stones, burial cairns and cists, along with hut circles and an extensive field system, that date back to between 3500 and 1500 BC. The circles were erected in about 2000 BC but archaeologists have found these were preceded by timber circles. The stones circles were built later on exactly the same sites as the wood.

Crowning a large knoll and surrounded by fields just near the border with Scotland, this rough circle of five standing stones was constructed around 4,000 years ago. The weathered sandstone rocks certainly look their age. It’s thought there were originally six megaliths in the monument, which encircled a central pit, where archaeologists found remnants of charcoal and bone.

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This 7,000-year-old megalithic monument in Spain’s Extremadura region is particularly intriguing because it only recently reappeared, after being submerged for decades beneath a reservoir. Around 100 ancient stones, thought to have been used as a ceremonial tomb, are arranged in an oval shape. While the site was excavated in the 1920s, it was later flooded after a dam was built. The dolmen was revealed in summer 2019 after a period of drought.

The Bronze Age ring cairn of Bryn Cader Faner would once have marked a burial site. With its name translating as “the hill crowned with the throne of the flag jagged slate”, the spiky structure is an arresting sight amid a lonely patch of moorland in the brooding hills of Snowdonia. The 4,000-year-old formation has around 15 long, thin stone slabs of slate that lean outwards, reminiscent of a crown of thorns.

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The second largest stone circle in England, Long Meg and Her Daughters has 69 stones with a diameter of about 350 feet (106m). Long Meg, the largest of the megaliths, sits apart from the circle and bears three mysterious symbols. The sacred site, thought to date to 1500 BC,  lies near Penrith in Cumbria. It was likely constructed as a meeting place or used for spiritual ceremonies. Local legend has it that Long Meg was a witch who was turned to stone for dancing on the Sabbath along with her pagan daughters.

The Carnac Stones or Carnac Alignments in northern France is the largest megalithic site ever found. Built by pre-Celtic inhabitants of Brittany between 5000 and 2000 BC, nearly 3,000 ancient menhirs stand in rows while other types of megaliths are arranged in clusters. The main group has 12 converging rows of standing stones, stretching over half a mile (1km) with the remains of a stone circle at either end. Shrouded in mystery, local legend refers to them as a stone army while historians believe the site was of great ceremonial and religious significance to its creators.

Vast and ancient deer stone monuments are scattered across the central Asian steppe, built by Mongolian Bronze Age nomadic pastoralists along with ceremonial or burial mounds (khirigsuurs). The large and imposing stones, which often feature elaborate carvings of flying deer, can be arranged in groups or lone monoliths. Small circles of stone boulders have also been found around khirigsuur in the Altai Mountains, a fertile region for archaeologists studying Bronze Age hunters and herders.

Deep in a thick forest in central Poland, the Iron Age rings of Odry are a beautiful oddity. No one is certain exactly when or why they were built and they have long been shrouded in local legends and witchcraft, but four of the stone circles are connected to solstices. With at least 602 Neolithic burial sites and Europe’s second largest collection of circles, it's a significant site for historians studying the Wielbark culture in Pomerania, a historic region that covers parts of Poland and eastern Germany.

At the foothills of the Pyrenees in the eastern part of the province of Guipúzcoa, the Aiako Harria Natural Park is a place of great beauty. And the ancient granite massif is a hotbed of remains from prehistoric cultures too. There are age-old dolmens, burial mounds and cromlechs (stone circles) – remnants of funeral rituals practised by the Neolithic peoples of this area. The Cromlech of Oianleku is a spectacular one.

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Given its scale and significance to Neolithic Britain, Stanton Drew is surprisingly little-known. The three stone circles in a small Somerset village make up the third-largest complex of prehistoric standing stones in England, dating back about 4,500 years ago. The largest of the three, the Great Circle, measures 310 feet (113m) in diameter and has 26 upright stones. It’s thought the circles were erected as part of an elaborate ceremonial monument – a geophysical survey found remains of a complex pattern of buried pits, arranged in nine concentric rings within the stone circle, and further pits at the centre.

As a region steeped in myths and legend, it’s no surprise that Cornwall has its fair share of mystical stone circles. Boscawen-un, near St Buryan, is a Bronze Age ellipse circle with a striking leaning granite standing stone. It is etched with what appears to be two crude stone axes at its base and encircled by 19 other upright monoliths – all made of granite except one that is mysteriously quartz.

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The high moorlands of Devon have some of richest Bronze Age remains in all of Britain, including many stone circles. There are 14 in the beguiling landscape of Dartmoor alone. One of which is Scorhill, a striking circle of tall granite stones on Gidleigh Common. There are 23 still standing while 11 have fallen onto moorland over the centuries. The tallest stones, which stand at over eight feet (2.5m) high, frame the sunset during the midsummer solstice, suggesting it may have been an astral timepiece.

Surprisingly little is known about the origins of the large groups of stone circles that are scattered around Senegal and the Gambia. The vast sacred landscape, created over more than 1,500 years, is an UNESCO World Heritage Site known as the Stone Circles of Senegambia. It encompasses four large groups of stone circles, including the 11 ancient stone circles of Wassu which are found around the Central River Region of Gambia. Constructed by an ancient African culture, Wassu has the tallest stones and some burial remains.

Another awe-inspiring example of this west African megalithic tradition is Senegal’s Sine Ngayene. The extraordinary complex is the largest of the four groups in the UNESCO property. It has 52 circles of standing stones, including one that forms a double circle. You can also see the quarry from where the mighty monoliths were painstakingly extracted. The site also includes numerous burial mounds, suggesting they have a funerary function.

A bird’s-eye view gives you the best sense of the scale and ambition of this ancient megalith monument that lies in the Israeli-occupied portion of the Golan Heights. Consisting of a large circle of basalt rocks and four smaller concentric circles, the site was only discovered in 1967 by Israeli archaeologists after the territory was captured from Syria. It’s been dated to 3000 BC but exactly who built it and why is unknown.

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It might not be ancient but this full-scale replica of Stonehenge in Maryhill, Washington is an impressive site. Set just east of the Maryhill Museum of Art, it was built by the museum’s founder Sam Hill in 1918 to commemorate 14 servicemen of Klickitat County. It was the nation’s first First World War memorial and every year a remembrance ceremony is held on the anniversary of the death of each of the men. Hill’s ashes are in a crypt housed just below the memorial.

Jutting out from the earth below the brooding Hebridean sky, the Calanais Standing Stones (also known as the Callanish stones) are a majestic sight. Set on the west coast of Lewis, the most northerly island in the Outer Hebrides, the prehistoric structure is made from gneiss rock and is more than 5,000 years old. It’s thought it was used as a kind of astronomical observatory. 

No matter how many times you gaze upon the mighty circle of stones rising from the Salisbury Plain, you'll always be awestruck by them. The most famous prehistoric monument in Europe, Stonehenge was erected in the late Neolithic period in around 2500 BC and is now part of an UNESCO World Heritage Site along with nearby Avebury. The mystery of how and why the enormous sarsen stones and smaller bluestones were transported all the way from Pembrokeshire and erected here has fascinated people for centuries.

While it's widely known Stonehenge's smaller bluestones came from Wales, evidence has suggested that part of the famous stone circle was first built at a site called Waun Mawn, near the Pembrokeshire Coast, before it was dismantled and rebuilt in Wiltshire. Archaeologists found the same rock type in both sites, plus a bluestone from Stonehenge that has the exact same unusual cross-section left behind in a hole at Waun Mawn, suggesting the monolith began its life as part of a stone circle in the Preseli Hills (pictured).

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An ancient stone circle has just been found at a prehistoric ritual site in Cornwall, UK. Seven regularly spaced pits, placed in a horseshoe formation, have been dug out by archaeologists. However, experts have speculated that it used to form a complete ring before ground conditions transformed the shape. It is believed that Castilly Henge was built between 3000-2000 BC and was used for gathering and ritual activities.