"To keep milk from turning sour: Leave it in the cow."
There's a lovely logic to that; can we apply it to the future of Stonehenge?

Wot, like to avoid erosion, ban visitors?

Which reminds me. Too many people want to go there. So there's only one solution, like it or not. Rationing.

I think if we're going to do that it would be best to have a merit system. Those who deserve it most get a longer visit. This could be easily arranged by asking a simple question of visitors -
"Stonehenge - what's it all about?"

According to the answer given the length of visit would be granted. EG. -
"Lizards built it" (1 second).
"Aliens made it" (10 seconds)
"It's ritual" (0 seconds)
"It's a Temple maaan" (O seconds, a crate of beer and a free bus trip to Foamhenge)
"I'm from Heritage Action" (24 hours and a free tent).