A very large enclosure and complex of stone settings, Avebury is a Late Neolithic ritual site in central-southern England that is so well preserved in its earth-built features that it shows well the grandeur of these places in their original scale.
At Avebury, a roughly circular area some 985 feet (300 m) in diameter is enclosed by a deep ditch, dug into the chalk. The spoil dug out from it was piled into a bank, set outside the ditch. Even today, after some 4,500 years of erosion, the crest of the bank stands up to 26 feet (8 m) above the ditch floor. Originally the bank was higher, and the ditch was nearly twice its present depth; a photograph from the excavations at the turn of the twentieth century shows the workmen standing on the giant steps that they had cut, one above another, deep into the accumulated fill. As is characteristic of the henge monuments of which Avebury is a very splendid and very large example, the bank is on the outside, where it would give attackers the advantage over defenders inside; for this reason the henges are not thought to be defensive in intent.
Round the inner edge of the enclosed circular area runs a setting of well-spaced and unshaped sarsen stones, one of the largest of British stone circles. There were further stone settings inside, more circles, and a “cove” constructed of three great slabs that stood together to make an open-ended box. From one of the original four entrances, an “avenue” made of paired upright stones ran along a valley for .6 miles (1 km) to the sanctuary, a small stone circle recorded by William Stukeley in the eighteenth century before a farmer broke the stones up. The stones of the main Avebury circles were, for the most part, buried or broken up either in medieval times or about Stukeley's day. The ones seen now were for the most part excavated and reerected in position in the 1920s and 1930s. The many eighteenth-and nineteenth-century houses in the modern village of Avebury that are built of broken sarsen blocks are further memorials to what has gone. Air photography has detected some sites flattened completely by plowing; nearby, another great circular enclosure, demarcated by a palisade fence of close-set posts, came to light in the 1980s.
In the environs of Avebury are many other important sites of the Neolithic and Bronze Age. The most famous and puzzling is Silbury Hill, a giant flat-topped barrow that is the largest artificial mound of prehistoric Europe; its exploration by shaft and by tunnel in the nineteenth and twentieth centuries has found no burial at its center. The nature and purpose of Silbury Hill, which dates a little later than Avebury and broadly contemporary with Stonehenge, remains unknown. Above Avebury, on the summit of Windmill Hill, is a smaller, slighter, and older circular cause-wayed enclosure which may have functioned as its predecessor.
This ritual landscape of sacred and ceremonial sites around Avebury echoes the similar complex around Stonehenge, about 19 miles (30 km) to the south. Avebury, reckoned to date a few hundred years earlier than Stonehenge, shares many features with its more famous sister monument. Each has settings of stone circles within a bank and ditch, and the entrance approach to each is marked by a long avenue. Yet the particulars are different. Avebury is very large, and Stonehenge is small. The Avebury stone circles, made of the same sarsen rock, are unshaped, well spaced, and have no horizontal lintels, whereas the Stonehenge sarsens are shaped, close-set, and support lintels. The Avebury avenue is of parallel lines of stones, and the Stonehenge avenue is of parallel banks of earthy chalk. The same goes for the ritual landscapes of their environs, which have a profusion of burial mounds in common, and other earth, wood, and stone structures each peculiar to that particular complex. [See also British Isles: Prehistory of the British Isles; Camps and Enclosures, Causewayed; Stone Circles and Alignments.]