aerial photograph of Silbury Hill Wiltshire England UK. Silbury Hill is a prehistoric man made hill constructed in the Late Neolithic / early bronze age around 2400 BC.The artificial mound is around 40m high and built from the clay and chalk of the surrounding land. It is estimated that it would have taken around 18 million man hours to construct and so can only have been accomplished by a well organized and advanced civilization. A later Roman settlement has been found adjacent to the hill and the nearby Roman Road was built to curve round the monument.The site is a UNESCO World Heritage Site and also a Site of Special Scientific Interest..Silbury Hügel , eine künstlich Hügel aus den Jungsteinzeit um 2400 vor Christus.