The Pantheon's extraordinary dome-shaped roof, is the largest unreinforced concrete dome in the world to this day. But that’s not all that’s special about this ancient ceiling.
Considered one of the most beautiful coffered ceilings in the world, its patchwork pattern of depressed cubes surrounds a nine-meter hole - known as the oculus - directly in the dome’s center. The hole serves multiple functions, the first is that it helps to alleviate structural tension at the weakest part of the dome. It also fills the space with natural light and makes lovely moving shadow patterns on the squares.
No matter the time of year, this hole is never covered, so bear that in mind when you visit. Your perfect moment in the spotlight might be washed out quicker than you might think!