Construction of the Pantheon

Emperor Hadrian directed construction of the Pantheon in Rome between approximately 118-126 CE, replacing an earlier temple by Marcus Agrippa. The structure combined a rectangular portico with Corinthian columns and a circular rotunda topped by a concrete dome measuring 142 feet in diameter. The dome featured a 30-foot circular opening (oculus) providing the primary light source. Roman engineers varied the dome's thickness from 21 feet at the base to 4 feet near the oculus, using progressively lighter materials toward the top. The building remains largely intact after nearly 2,000 years and influenced later domed architecture.