"The riddle of Silbury, unsolved after 4,300 years"
http://www.timesonline.co.uk/tol/comment/columnists/richard_morrison/article2771879.ece
Someone is having fun with foolish speculation....
"All that effort, planning and ingenuity, gone into producing a monument to a belief, a person, a regime, an event, that must have seemed frightfully important at the time, yet is now totally erased from human chronicle and consciousness. Few other places on the planet induce so profound a sense of mankind’s microscopic insignificance when measured on cosmic timescales. "