Silbury Hill, part of the complex of Neolithic monuments around Avebury in Wiltshire (which includes the West Kennet long barrow), is the tallest prehistoric man-made mound in Europe and one of the world's largest.
On a base covering over 2 hectares (5 acres), it rises 39.6m (130ft) high. It is a display of immense technical skill and prolonged control over labour and resources.
Archaeologists calculate that Silbury Hill was built about 4600 years ago and that it took 18 million man-hours to dump and shape 248,000 cubic metres (8.75 million cu ft) of earth on top of a natural hill. Every man, woman and child in Britain today could together build such a mound if they each contributed one bucketful of earth.
The base of the monument is 167m (550ft) in diameter and it is perfectly round. Its summit is flat-topped and 30m (100ft) wide. We know that the construction took two phases: soon after work was started, a re-design was ordered, and the mound enlarged.
It is constructed in steps, each step being filled in with packed chalk, and then smoothed off. There have been three excavations of the mound: the first when a team of Cornish miners led by the Duke of Northumberland sunk a shaft from top to bottom in 1776, another in 1849 when a tunnel was dug from the edge into the centre, and a third in 1968-70 when professor Richard Atkinson had another tunnel cut into the base.
Nothing has ever been found on Silbury Hill: at its core there is only clay, flints, turf, moss, topsoil, gravel, freshwater shells, mistletoe, oak, hazel, sarsen stones, ox bones, and antler tines.
Moses B.Cotworth, at the beginning of this century, stated that Silbury was a giant sundial to determine seasons and the true length of the year. More recently, the writer Michael Dames has identified Silbury Hill as the winter goddess but he finally acknowledges that the monument remains a stupendous enigma.
According to legend, this is the last resting place of King Sil, sitting on a fabled golden horse. Another legend states that the mound holds a lifesize solid gold statue of King Sil and yet a third, that the Devil was carrying an apron of soil to drop on the citizens of Marlborough, but he was stopped by the priests of nearby Avebury.
The West Kennet Long Barrow is situated on a ridge one-and-a-half miles south of Avebury in Wiltshire. The photograph at left, taken from a point on the Ridge Way near the Sanctuary, shows the placement of the barrow within the surrounding landscape and the low ridge upon which it sits.
The site was recorded by John Aubrey in the 17th century and by William Stukeley in the 18th century. Aubrey describes it as "On the Brow of the hill, south from the west Kynnet" (i.e. the River Kennet, see Silbury Hill for some comments on this stream), and adds that it is "without any name."
Stukeley observes that "It stands east and west, pointing to the dragon's head on Overton-hill." The barrow is marked on Stukeley's drawing of the 'great stone serpent' of Avebury in which one can also see Overton Hill (also called The Sanctuary by Stukeley).
The barrow was dug into in in 1859, and properly excavated in 1955-56. It originally consisted of a trapezoid mound 330 feet long formed of a core of sarsen boulders and a capping of chalk rubble from two flanking quarry ditches.
At the eastern end of the mound is an elaborate megalithic structure of five chambers opening off an axial passage. The entrance passage is fronted by a semi-circular forecourt with a flanking facade of massive sarsen uprights aligned along a north-south axis.
The photograph at left shows the interior with the chambers located off the axial gallery. A minimum of 46 individuals of all ages and both sexes, together with many pottery sherds, flint implements, beads and other objects, were discovered in the course of excavation.
The burials evidently took place over a considerable period of time. It appears that a number of the bones, mainly skulls and thigh bones, were abstracted from the tomb at different times, possibly for ritual purposes.
At some point the chambers and passage were filled with chalk rubble and the semi-circular forecourt blocked with a filling of sarsen boulders. At this time, it seems, a 'false entrance' of twin uprights was erected, and three massive blocking stones placed in line across the entrance to the forecourt. This final blocking and closure of the tomb appears to have occurred around 1600 B.C.E.