The Pantheon is composed of several distinct architectural structures, including a portico of large granite Corinthian columns, a pediment, a rotunda, and a hemispherical dome. The portico is the entrance to the Pantheon and is composed of 16 granite Corinthian columns. The pediment is a triangular structure that sits atop the portico and is decorated with relief sculptures. The rotunda is the main chamber of the Pantheon and is circular in shape. The hemispherical dome is the most iconic feature of the Pantheon and is made of concrete and brick. It is 43 meters in diameter and is topped with an oculus, or opening, at the center.
