Pantheon was built as a temple of the official religion in ancient Rome. Built around 118 - 128 AD it is one of the best preserved buildings of ancient Rome. Pantheon is famous for its large granite Corinthian columns and a central roof opening to the sky.

The opening (oculus) of the dome and the entrance door are the only sources of light inside. A drainage system under the floor takes care of the rain water that falls through the oculus. Pantheon's oculus also serves as a cooling and ventilation system. It is still the world's largest concrete dome built without any kind of reinforcement.