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, .