The interior of the Pantheon, the oldest domed building. It was built by Hadrian from A.D Rome Italy (there are no chairs and tired tourists are not allowed to sit down to rest, if even only to stare up at that beautiful dome)
Trevi Fountain in Rome, Italy -- "the fountain at the junction of three roads." Throw a coin into the fountain, and legend has it that you will return to Rome. I wish I'd tossed a coin in while I was there!