ROME, ITALY - JUNE 03: Illustration of Rome; Italy on June 03, 2012 .Piazza della Rotonda. The Pantheon (from Greek, an adjective meaning "to every god") is a building in Rome, Italy, commissioned by Marcus Agrippa as a temple to all the gods of Ancient Rome, and rebuilt by Emperor Hadrian in about 126 AD..Almost two thousand years after it was built, the Pantheon's dome is still the world's largest unreinforced concrete dome. The height to the oculus and the diameter of the interior circle are the same, 43.3 metres (142 ft)..It is one of the best-preserved of all Roman buildings. It has been in continuous use throughout its history, and since the 7th century, the Pantheon has been used as a Roman Catholic church dedicated to "St. Mary and the Martyrs" but informally known as "Santa Maria della Rotonda." The square in front of the Pantheon is called Piazza della Rotonda...In the aftermath of the Battle of Actium (31 BC), Marcus Agrippa built and dedicated the original Pantheon during his third consulship (27 BC). Located in the Campus Martius, at the time of its construction, the area of the Pantheon was on the outskirts of Rome, and the area had a rural appearance. Under the Roman Republic the Campus Martius had served as a gathering place for elections and the army.