London 101 though: It's tricky to see Big Ben as it's one of the bells housed inside the tower. The tower is officially called "Elizabeth Tower" (recently changed from the "Clock Tower" in honour of the Jubilee).

There are tours to see the bells (and Big Ben itself) but they seem to be only available to UK residents via their MPs. I've never bothered to try (I'd rather sort out a tour of Lord's cricket ground first).