Among the buildings of classical antiquity, the Pantheon is certainly the best preserved, by virtue of its transformation into a church (Santa Maria ad Martyres) in 609 AD.

The original building was erected between 27 and 25 BC at the behest of Marcus Vipsanius Agrippa in honour of Augustus and then dedicated to the main deities of the Julius Claudia family.

Its present form dates back to the early years of Hadrian’s reign (118-125 BC). An enormous cylindrical wall (the Rotunda) more than 6 metres thick supports the monumental vault, the largest dome made of Roman concrete, 43.30 metres in diameter and the same height.