Of that list, I'd have to say the Leaning Tower of Pisa. Get off the train, make your way to the tower (I either walked or took a bus, can't remember), take some pictures, get on the next train out of town.

Genova Italy is just as bad. I had to crash there one night and was glad to get the heck out.

Las Ramlas, Spain was quite nice, except for my brother getting his camcorder stolen.