Surrounding part of Avebury village, the Avebury Stone Circles, the largest in the world, are one of England's most evocative prehistoric monuments—not so famous as Stonehenge, but all the more powerful for their lack of commercial exploitation. The stones were erected around 2600 BC, about the same time the better known monument. As with Stonehenge, the purpose of this stone circle has never been ascertained, although it most likely was used for similar ritual purposes. Unlike Stonehenge, however, there are no certain astronomical alignments at Avebury, at least none that have survived. The main site consists of a wide, circular ditch and bank, about 1,400 feet across and more than half a mile around. Entrances break the perimeter at roughly the four points of the compass, and inside stand the remains of three stone circles. The largest one originally had 98 stones, although only 27 remain. Many stones on the site were destroyed centuries ago, especially in the 14th century when they were buried for unclear reasons, possibly religious fanaticism. Others were later pillaged in the 18th century to build the thatched cottages you see flanking the fields. You can walk around the circles at any time; early morning and early evening are recommended.