Italy 2012 / 20120606e_RomePantheonOculus Ruth Milner, rmilner plus web at bookofmarvels dot net 3/18/2013

Pantheon, Rome The oculus, or light-well, at the top of the Pantheon dome. Although it is very hard to tell from the floor, the oculus is more than 25 feet in diameter. The floor is designed with a very slight concave shape, with small holes and a drainage system beneath it to handle rainfall.