Pantheon oculus

Pantheon, Rome, 126 AD

The Pantheon is a building in Rome, commissioned by Marcus Agrippa as atemple to all the gods of Ancient Rome, and rebuilt by Emperor Hadrian in about 126 AD. The building is circular with a portico, under a coffered, concrete dome, with a central opening to the sky, called Oculus. 

Inside the Pantheon

The oculus at the dome's apex and the entry door are the only sources of light in the interior. Throughout the day, the light from the oculus moves around this space in a sort of reverse sundial effect. The oculus also serves as a cooling and ventilation method. When the rain is lighter, the temperature difference between the interior and the exterior of the Pantheon origins an air draught that comes out trough the oculus don't allowing rain to enter. Naturally, during storms, a drainage system below the floor handles the rain that falls through the oculus.

Oculus shadow on the dome

@ View panorama from the inside of the Pantheon