Okay, so the Pantheon has got to be one of my favorite parts of all Rome. No lies here. Not only is it one of the greatest architectural achievements of the ancient world (yes I realize that’s an opinion), it inspired famous architects for centuries to come, including the several involved in the construction of St. Peter’s Basilica. It’s also a great example of the Roman’s propensity for stealing stuff from Egypt. The single-piece granite columns and the obelisk outside were both stolen from Egypt.
So here’s a brief rundown. The thing can fit a sphere perfectly inside of it  feet tall. It was made with concrete (which the Romans invented along with plywood shields) and is designed to have nifty square bits in the ceiling. This combined with a lighter form of concrete (they mixed in pumice instead of something like travertine) made it possible to construct the dome.
Yeah. This isn’t a new roof. It’s almost two thousand years old. Two millennia. Twenty centuries. Two hundred decades.
Anyway, the Pantheon houses the first Emperor/King of Italy (from the late 1800’s) and his queen who was called, get this, Margarita. From which “Pizza Margarita” got its name.
Also in attendance is the very great Raphael. Super famous painter dude. We’ll have more on him in the Vatican.
For those interested, the caption on his tomb says “In life, Nature feared to be outdone by him. In death, she feared she too would die” in Latin.
One last note, because I need to rant. The Pantheon managed to survive the centuries for mostly one reason: its massive “pagan” statues got tossed out and it was converted into a church. Which I guess is preferable to its destruction, but how much cooler would that thing have been with a thirty/forty foot tall Jupiter staring down at you?