An iconic structure in Rome that deserves a visit!
If you ever go to Rome, be sure and visit The Pantheon. This former pagan temple is now a Christian Church, and it's stunning. It has a huge oculus in the domed roof that is nearly 8 meters across, and is the only source of light in the structure. There are amazing frescoes and tombs inside, and it's free, too. Just show up and walk in (but don't forget the camera)!
I was there one evening and just loved the scene in front of the Pantheon, with the open courtyard, fountain with obelisk, and just the general look of the place. So beautiful! It's also a very busy place, so expect to see a lot of people there, at basically any hour of the day. But nonetheless, brave the crowds and get a taste of history.