Another of the great prehistoric mysteries still with us in Britain is Silbury Hill, which is situated not far from the recently mentioned Avebury.
Many consider Silbury to be part of the Avebury complex. Silbury is the tallest prehistoric man-made hill in Europe. It is 130 feet high, and its base has a diameter of 550 feet and covers more than five acres; the summit is 100 feet wide and is nearly completely flat. Scientists have speculated that the building of the mound took 8.75 million cubic feet and 18 million man-hours. All this was done 4,600 years ago, with whatever primitive tools were available. (This is the same time periods as the Pyramids at Giza.)
Why was this mound made? Why was it constructed where it was? Was it a hill-fort? Was it part of the Avebury series of astronomical observation complex, as many scientists now conclude? Was it a giant sundial, as others have suggested? Was it a burial mound for a long-forgotten King Sil? No one knows still.
Scientists do know that the mound was constructed in three phases, based on examinations at the site. It has also been observed that Silbury Hill is smack in the middle of a Roman road between Marlborough and Bath. (Oddly enough, this Roman road runs straight between the two places, except at Silbury, where it swerves to go around the mound.) Silbury has also been observed to be part of one of the ancient many meridian and ley lines of stones and mounds dotting Britain.
In all, three major excavations have been made. One was a top-to-bottom shaft dug way back in 1776; the other two were tunnels, from the edge into the center, one in 1849 and one in 1970. None of these excavations recovered any sort of evidence to prove any one theory. In fact, only natural materials were recovered.
Evidence has been recovered, however, to suggest that the mound was first built at the time of year of the Celtic festival of Lugnasadh, the start of the harvest season. This would seem to suggest the importance of the calendar and of respect or veneration for deities of some sort.
Given the lack of evidence discovered to support the theories of burial ground or hill-fort (and the excavations would seem to have been sufficient to have uncovered something of that nature if it were there, one can likely conclude that the astronomical theory is a likely candidate at this point. This theory about megaliths and standing stones is gaining credence in many circles, in arguments about Stonehenge and Avebury. Perhaps it was the case with Silbury as well (although the name itself is conveniently close to “burial ground of Sil,” if taken literally).