QUOTE
In June 2000, a large hole suddenly appeared on the top of Silbury Hill, Europe's largest prehistoric artificial mound and a key feature of the Avebury World Heritage Area. It was soon clear what had happened: the head of an old excavation shaft, dug in 1776 to penetrate to the heart of the enigmatic Neolithic monument, had begun to collapse. English Heritage immediately embarked on a programme of research to understand why this had taken place and find out if the situation was likely to get any worse. As soon as we understood the nature of the collapse, we began work to arrest it and return the ancient monument to its former glory.
Read the whole article and the reports here:- http://www.english-heritage.org.uk/server/...00100200800i002
I love this place - its just such a beautiful monument... and the pictures give you no idea on how big it is generally - its an awe inspiring monument.
Here is a picture I took last year...