This report gives a full account of: the excavation of Silbury Hill in the late 1960s; environmental evidence from the tunnel and the ditch section; the cuttings on top of the mound; and the radiocarbon dates. Enclosures at nearby West Kennet, first seen from the air in 1950, have been the subject of research excavations since 1987. One is a nearly circular double enclosure that straddles the present Kennet, the other is a larger ellipitical enclosure...