Using your post ED (slightly edited) how about this on a separate thread entitled Trespassing on Silbury Hill: An open letter to English Heritage.
Dear English Heritage.
Following on from recent reports in the media, contributors to this board and elsewhere have become increasingly alarmed at the damage being caused to Silbury Hill by people ignoring your signs that ask them not to climb the monument. Many of us feel strongly that the signage is both inadequate and strikes the wrong note. We therefore suggest something along the lines of the following: a number of signs placed at sensitive points of (unauthorised) access to the monument, displayed in two or three languages and reading -
Some, no doubt well meaning, old archaeological investigations, have compromised the integrity of this hill. At one point it was in a very real danger of collapsing. It is still in a very fragile state. Some people, in trying to feel as close a bond as possible, perhaps, to our ancestors and to our past, like to climb the hill. Many do not realise the damage that is done by what amounts to thousands of people walking on the hill over many years. We also know that most of those people would be horrified if they realised the damage they were inadvertently causing to such a precious monument.
We know you might like to climb this hill. We would too. But please don't.
We want it to still be here in another 4,000 years for others to marvel at as you do, and when you leave this place today we would like you to feel you have played your part in its survival.
Thank you and please enjoy your time here.