An incredible example of Roman building techniques , this was originally the site of a Roman temple built by Emperor Agrippa between 27-25BC by an unknown architect. The current building dates back to the period of Emperor Hadrian when he had it rebuilt in 125AD. The dome is a perfectly constructed hemisphere , the diameter is the same as its height, and has an open circle at the apex, or the eye to the gods. This was the largest dome until Brunelleschi's one in Florence. What once was a one stop Roman gods shop, where seven deities were housed in the niches, became a Christian church in the 7thC and is now home to the remains of Raphael and two Italian kings. The Pantheon is open from 8:30 a.m. to 7:30 p.m. Monday to Saturday, from 9 a.m. to 6 p.m. on Sunday, and 9 a.m. to 1 p.m. on holidays that fall on weekdays except for Christmas Day, New Year's Day and May 1, when it is closed. Admission is free.