Composed principally of chalk, the mound stands 130 feet (40 meters) high, and covers about 5 acres (2 hectares). The chalk used in the construction of the mound was excavated from the area around the mound, forming an enormous ditch encircling the hill. Today the ditch is largely silted in.
The exact purpose of the hill is unknown. It is possibly a burial tomb, though no remains have been found. There are several legends regarding the hill.
Excavations in 1776, 1849 and 1968 revealed little. A recent collapse of the 1776 excavation shaft caused a hole to form in the top of the hill.