ving have been uncovered by various excavations, it is possible to estimate its construction. The forecourt was probably a paved space with three sides surrounded by covered colonnades. The paved court probably extended 300 feet to 400 feet from the north end of the temple front. A triumphal arch stood on the central axis of the court. It carried reliefs showing information on the emperor. The forecourt entrance was a formal columned gateway on the northern end.
On the south side of the rotunda are the remains of a great hall. Its axis is perpendicular to that of the Pantheon, and it abuts the south wall. This building may be the Basilica of Neptune, built by Agrippa and rebuilt by Hadrian. The building appears to be a part of the Pantheon but actually is not, because it has no accessáto the rotunda.
The construction of the Pantheon was made possible because of the mastery of brick-faced concrete as a construction material. The rotunda is made from brick-faced concrete and rests on a ring of concrete. The rotunda is capped by a perfect half sphere, and the outside of the dome is stepped,
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