Ring of Brodgar, Orkney

Taken from Wikipedia: The Ring of Brodgar is a Neolithic henge and stone circle in Mainland, Orkney, Scotland. It is the only major henge and stone circle in Britain which is an almost perfect circle. Most henges do not contain stone circles; Brodgar is a striking exception, ranking with Avebury and Stonehenge among the greatest of such sites. The ring of stones stands on a small isthmus between the Lochs of Stenness and Harray. These are the northernmost examples of circle henges in Britain. Unlike similar structures such as Avebury, there are no obvious stones inside the circle, but since the interior of the circle has never been excavated by archaeologists, the possibility remains that wooden structures, for example, may have been present. The site has resisted attempts at scientific dating and the monument's age remains uncertain. It is generally thought to have been erected between 2500 BC and 2000 BC, and was, therefore, the last of the great Neolithic monuments built on the Ness. A project called The Ring of Brodgar Excavation 2008 was undertaken in the summer of that year in an attempt to settle the age issue and help answer other questions about a site that remains relatively poorly understood. The results of the excavation are still preliminary. The stone circle is 104m (341 ft) in diameter, and the third largest in the British Isles. The ring originally comprised up to 60 stones, of which only 27 remain standing. The stones are set within a circular ditch up to 3 metres (9.8 ft) deep, 9 metres (30 ft) wide and 380 metres (1,250 ft) in circumference that was carved out of the solid sandstone bedrock by the ancient residents.[7] Technically, this ditch does not constitute a true henge as there is no sign of an encircling bank of earth and rock. The ditch appears to have been created in sections, possibly by workforces from different parts of Orkney. The stones may have been a later addition, maybe erected over a long period of time.  The site is a scheduled monument and has been recognized as part of the "Heart of Neolithic Orkney" World Heritage Site in 1999.