The Pantheon is a building in Rome, originally built by Marcus Agrippa as a temple to all the gods of Ancient Rome, and rebuilt in the early 2nd century AD. The building is circular with a portico of three ranks of huge granite Corinthian columns (eight in the first rank and two groups of four behind) under a pediment opening into the rotunda, under a coffered, concrete dome, with a central opening (oculus) open to the sky. Almost two thousand years after it was built, the Pantheon's dome is still the world's largest unreinforced concrete dome |