Got a thirst for the ancient or just itching to see what all the fuss is about with Roman engineering? The Pantheon in Rome is your ticket to awe. This architectural behemoth isn't just old; it's an enduring masterpiece that's been kicking around since 126 AD, courtesy of Emperor Hadrian. Originally a temple to all the gods (yep, that's what "Pantheon" means), it's now a church with a hole in the roof that does more than just let the rain in. It's a marvel of the ancient world that's still standing strong, and it's free to visit.

Best time to go? This beauty's a year-rounder, but if you want that perfect light show through the oculus (the fancy name for the roof hole), midday, when the sun is high, is when you'll get those Instagram-worthy shots. But honestly, rain or shine, you're in for a treat.