Carbon dating suggests that Silbury Hill was built around 2500 BC (the same era as the
Silbury Hill is the largest man made mound in Europe, the second largest is Marlborough Mound just a few miles to the east in the grounds of Marlborough Nobody really knows why it was built, local legend would have it as the burial place of King Sil (or Zil), said to buried under the mound sitting on his horse. There have been several excavations which have not found any trace of a burial.
The original purpose of Silbury is unknown, although various explanations have been put forward over the years. Recently, Michael Dames has suggested that the hill is a symbolic effigy of the ancient Mother Goddess and is to be associated with fertility rituals which marked the course of the year. The festival of "Lugnasadh" (or Lammas) in August, when it is thought Silbury was founded, celebrates the first fruits of the harvest. It has been pointed out that the spring which rises five hundred yards south of the hill and is the source of the River Kennet, was formerly called the Cunnit, a name which may be connected to the Mother Goddess and fertility.
Another explanation argues that Silbury Hill could have been used as an accurate solar observatory by means of the shadows cast by the mound itself on the carefully levelled plain to the north, towards Avebury. The meridian line from Silbury runs through Avebury church which stands on a ley line running between Stonehenge and the stone circle at Winterbourne Abbas. The same ley line also passes through two churches and the eastern slope of Silbury. Silbury, in fact, is a centre for alignments of straight prehistoric tracks, resurfaced by the Romans, and of standing stones.