The Pantheon is a building in Rome, Italy, commissioned by Marcus Agrippa during the reign of Augustus as a temple to all the gods of ancient Rome, and rebuilt by the emperor Hadrian about 126 AD.
The building is circular with a portico of large granite Corinthian columns under a pediment. A rectangular vestibule links the porch to the rotunda, which is under a coffered concrete dome, with a central opening to the sky. 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, 43.3 metres.
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 dedicated to “St. Mary and the Martyrs”. As it is still a functioning church, silence is requested during your visit.
The Pantheon is celebrated for its large dome. From inside you’ll see traces of the former bronze ceiling, melted down during the reign of Pope Urban VIII. The hole in the center of the ceiling, though, is an original feature designed for architectural reasons (the dome would collapse without it.) If it happens to be raining, you should definitely go to the Pantheon to see the rain pouring into the building through the hole in the ceiling. There are holes in the ground that drain the water.
The spectacular doors are Romans, but not the original. The building now appears to be built in a depression, but this was not the original appearance. The street level at the sides and rear has risen about 10 meters since the original construction due to the accumulation of debris from 2,000 years of settlement.