Dome

General view, from the southeast, depicting the entire circular structure; The Temple of Hercules Victor or Hercules Olivarius, located in the Forum Boarium in Rome, is a monopteros, a round temple of Greek 'peripteral' design (surrounded by colonnades on all sides). This layout caused many to mistake it for a temple of Vesta, but it has been determined to be a temple of Hercules. Hercules was a favorite divinity for traders, so it is appropriate that it would be in a forum. Dating from about 120 BC, the temple is 14.8m in diameter and consists of a circular cella within a concentric ring of 20 x 10.66 m tall Corinthian columns resting on a tufa foundation. These elements supported an architrave and roof which have disappeared. The original wall of the cella and the columns remain but the current tile roof was added later. Palladio suggested a dome, though this was apparently erroneous. The temple is the earliest surviving marble building in Rome. By 1132 the temple had been converted to a church, known as St. Stephen 'of the carriages'. Additional restorations (and a fresco over the altar) were made in 1475. A plaque in the floor was dedicated by Sixtus IV. In the 17th Century the church was renamed St. Mary 'of the Sun'. Source: Wikipedia; http://en.wikipedia.org/wiki/Main_Page (accessed 7/9/2008)