The Pantheon (meaning "Temple of all the gods") is a building in Rome. It was originally built as a temple to the gods of Ancient Rome, and rebuilt about 126 AD during Hadrian's reign. Today, it is not known what gods were included.

The Pantheon is the best preserved of all Roman buildings. Since it was built, it has always been used. The design of the current building is sometimes credited to Trajan's architect Apollodorus of Damascus, but it may also been Emperor Hadrian's architects who designed it. Scholars now agree that it was not Hadrian himelf who built it. Since the 7th century, the Pantheon has been used as a Roman Catholic church. The Pantheon is the oldest standing domed structure in Rome. The height to the oculus and the diameter of the interior circle are the same, 43.3 metres (142 ft).

The Pantheon dome is the largest dome made mainly of unreinforced concrete. It does, however, contain other materials. According to the Jutland Archaeological Society investigations, the lower section of the dome is made of concrete with alternating layers of bricks and tuff; both have good affinity with the lime-pozzolan mortar which filled the voids.

The term pantheon is sometimes used for a building where well-known dead people are buried.

The interior of the Pantheon

Floor plan of the Pantheon from Georg Dehio/Gustav von Bezold: Kirchliche Baukunst des Abendlandes. Stuttgart: Verlag der Cotta'schen Buchhandlung 1887–1901.

The Pantheon dome. The coffered dome has a central oculus as the main source of natural light.

View of the Pantheon in Rome, including the concrete dome

An 1836 view of the Pantheon by Jakob Alt, showing twin bell towers, in place from early 17th to late 19th centuries.

The interior of the Pantheon in the 18th century, painted by Giovanni Paolo Panini.

The portico

Beam in the dome of the Pantheon

Low Memorial Library at Columbia University, designed by Charles Follen McKim

Pantheon during a cloudy day

South east view of the Pantheon from Piazza della Minerva, 2006

The Pantheon by night

Pantheon 2013

Sideways view across portico

Portico roof from below

Dome by night

Altar

Tomb of King Victor Emmanuel II, "Father of his Country"