Not only is this free to enter it has been recreated all over the world and was described by
Michelangelo as “of angelic and not of human design”.

The Pantheon as we know it today was constructed around 126 AD and was the third or fourth to be built as the others had all previously perished in fires. It was probably designed by the Greek architect Apollodorus of Damascus ( he was also the architect for Trajan’s column which can be seen in the forum) under the Emperor Trajan. The building was however completed under Hadrian and was for a long time thought to be built by him. Incidentally Hadrian later had Apollodorus banished and eventually put to death for critising his abilities as an architect and artist.

Pantheon

Pantheon


Despite the Pantheon being one of the most intact roman structures to survive its exact function is not known nor is its exact method of construction. Perhaps this is why it today remains the largest unreinforced concrete dome in the world and was the largest domed structure until the construction of the cathedral in Florence until 1436. The dome of the Pantheon is 43.3m tall and the interior circle has a diameter of the same size (therefore it would be possible for a sphere of 43.3m [142ft] diameter to fit inside the interior). The concrete dome weighs 4,535 metric tons and if it was made out of modern concrete would not be able to support its own weight.

The hole in the centre of the dome is know as an oculus and has a radius of 8.9 m. The oculus and entry doors are the only sources of light. When it rains the rain coming through the oculus is funneled into a drain under the floor by a slight slope in the floor level.

It is the consecration of the building in 609AD that saw the building persevered in such a high quality as many other roman buildings became abandoned, destroyed or pillaged. The Pantheon did not remain unscathed as the roof would initially have been covered with bronze tiles and the coffers contained bronze stars. Much of the bronze was melted down under the orders Pope Urban VIII (1623 to 1644) to make bombards for the fortification of Castel Sant’Angelo.