The Pantheon was commissioned by Marcus Agrippa as a temple to all the gods of Ancient Rome, and rebuilt by Emperor Hadrian in 126 AD. Almost two thousand years after it was built, the Pantheon's dome is still the world's largest unreinforced concrete dome. The height to the oculus and the diameter of the interior circle are the same, 142 ft. It is one of the best preserved of all Roman buildings. It has been in continuous use throughout its history, and since the 7th century, the Pantheon has been used as a Roman Catholic church informally known as Santa Maria Rotonda.
Do not confuse this Pantheon with Pantheon West, otherwise known as Hadrian's Temple.