Actually, Stonehenge was fairly interesting. To answer the MAQ: no, it's not fenced off. Well, it is fenced off from the roadway, so that you have to pay a few pounds to park and enter. And once inside, you get an audio tour handset. And there is a walkway delimited by some low ropes, to discourage you from running up and licking the stones. But I suppose if you felt you really needed to do so, you probably could, before one of the guides hurried in behind you to (politely, no doubt about it) request you desist.