There's a hole in the sky!!

 The Pantheon: the building with a giant hole in the ceiling. Don't get me wrong it's a beautiful building and there's lots of things to see, mainly dead people. The outside is magnificent and when you walk down to it -because it is built to the original ground level- it just gets bigger and bigger. The columns out front are very tall and you wonder 'how did people in ancient times build these things.'
Anyway the main thing is that there's a giant hole in the ceiling. There's no glass covering it and when it rains, well you get rained on if you stand under it. Literally the building is a round building with a whole in the top and I don't think there are any other doors that lead to rooms. It's pretty cool.