I didn't realize you were getting out to Salisbury! If you get half a chance, go see both Salisbury Cathedral and Old Sarum. Old Sarum is probably the best-preserved iron-age hill fort around, if you're into that kind of thing. The walls are so steep and the ditch around it is so big, that even after 1200 years of erosion, you could probably still defend it against hundreds of attackers with just a handful of defenders.

Yeah, I'm a history geek. :)