Silbury Hill is the largest prehistoric man made mound in Europe, standing 40 metres high and 167 metres in diameter at its base. Built around 4,600 years ago, it has been calculated that 18 million man hours were required to construct the hill in two distinct phases.

Excavations and digs in the last few centuries have revealed no obvious purpose for it's construction but have left the enormous mound in immediate danger of collapsing. Works are currently underway to secure and fill tunnels deep inside the mound and a shaft at it's core so the site is not currently visitable.

Silbury forms an intrinsic part of the wider archaeological landscape around Avebury and can be seen from many of the long barrows, mounds and earthworks surrounding it.