Silbury Hill is an artificial chalk mound near Avebury in the English county of Wiltshire. It is part of the Stonehenge, Avebury and Associated Sites UNESCO World Heritage Site.
At 40 metres (130 ft) high, Silbury Hill – which is part of the complex of Neolithic monuments around Avebury, which includes the Avebury Ring and West Kennet Long Barrow – is the tallest prehistoric human-made mound in Europe and one of the largest in the world; it is similar in size to some of the smaller Egyptian pyramids of the Giza Necropolis. Its purpose however, is still highly debated. There are several other Neolithic monuments in the area, including Stonehenge.