Bletchley Park is da Bombe
Went there last weekend, and it was completely awesome! Standing in a room with the clattering Colossus made the hairs on my neck stand up. And that was just the static :) And I saw the Holy Grail of Computing, aka Turing's tea mug - still chained to a radiator in Hut 8!
They are desperately short of funding though - the peeling paint and boarded-up windows say it all. Another £10m could see the place as a fantastic interactive museum of computing, codebreaking, and military history - with the Enigma vs Bombe and Lorenz vs Colossus as the centre-pieces.
Plus for some reason they have a Harrier Jumpjet, which is just completely sweet.