Conservationists are attempting to have Silbury Hill in Wiltshire reclassified as a building to protect one of the most enigmatic prehistoric structures in Europe. The move would reclassify the largest manmade mound in Europe. “The guardians of the 4,700-year-old hill have been trying to persuade people to keep off Silbury since 1974, when it was closed to the public, without destroying its appearance with intrusive fencing. The monument came close to destruction three years ago when torrential winter rain seeped into shafts left by earlier excavation, which collapsed. Although English Heritage has carried out repairs, the whole structure is vulnerable.”