The precise date of the Pantheon in Rome's original construction is difficult to say with precision, as the current building sits on the site of an earlier temple, which was commissioned by Marcus Agrippa during the reign of Augustus around 27 BC – 14 AD.
The Pantheon's predecessor was burned down, and the current temple was rebuilt by Emperor Hadrian around 126 AD. Formerly a pagan temple dedicated to all of the gods, the Pantheon was consecrated as a Christian church in the year 609.
Consequently, the building has been in continuous use ever since, which is the main reason why the Pantheon is one of the best-preserved architectural relics of the Roman Empire still standing today.