Silbury Hill is an artificial chalk mound near Avebury. At 121 ft high, Silbury Hill is the tallest prehistoric human-made mound in Europe and one of the largest in the world.
Archaeologists calculate that Silbury Hill was built about 4,750 years ago and that it took 18 million man-hours, or 500 men working for 15 years to construct.
Its purpose, however, remains shrouded in mystery. Excavations from the 17th century onwards have produced plenty of artefacts, but no reasons for its construction.
The Sanctuary is a prehistoric site on Overton Hill. Archaeologists believe that in around 3000 BC the site comprised six concentric rings of timber. These were replaced in around 2100 BC with two concentric stone circles.
Sadly the monument was destroyed in the 1700s. Concrete posts now mark the site of the timbers and stone rings.