The identity of the architect behind the Pantheon is unknown, but most scholars attribute it to Apollodorus of Damascus. The parts of Hadrian?s Pantheon are a columned porch (8 massive granite Corinthian columns in front, two groups of four behind), an intermediate area of brick, and finally the monumental dome. The Pantheon?s dome is the largest surviving dome from antiquity; it was also the largest dome in the world until Brunelleschi?s dome on the Duomo of Florence was completed in 1436.