The entire collection of Roman gods was called the Pantheon, and in fact in ancient times you could worship any of the gods whose statues were located in the niches in the Pantheon.

If modern unreinforced concrete were used in a building of the size of the Pantheon in Rome it would not stand under the load of its own weight. The composition of the concrete used in the dome is still unknown.

One of the most remarkable things about the Pantheon in Rome is that the inside dome is as high as it is wide, about 142 feet (43.3 m). The dome is the inspiration for many domes that came later including St. Peter's dome designed by Michelangelo and the dome in Florence designed by Brunelleschi. The dome of the Pantheon covers the entire hall making the impact more significant than domes that cover only a portion of a building.

A circular opening known as the oculus lets the only light in to the Pantheon. The oculus is about 30 feet across. The purpose of the oculus was not only to illuminate the interior but it was also built to let those in the temple contemplate the heavens.

The floor of the Pantheon is slanted to let rainwater drain from the building. The bronze doors of the Pantheon are among the few bronze doors from Roman times that have survived although they have been restored a number of times.

The Pantheon is the best preserved ancient building in Rome. In the 7th century, Christians claimed they were plagued by demons as they passed by the Pantheon. In AD 609, the Pantheon was consecrated and dedicated to Our Lady and all the martyers (it is known as the Church of Santa Maria ad Martyres). The consecration as a church ensured the Pantheon's preservation. The removal of any item, no matter how small or insignificant, would constitute a mortal sin.

In the 17th century pope Urban VII had the bronze ceiling from the portico melted down. Although there is some question as to what the bronze was used for it is thought that much of it went to build the canons in the Castel Sant'Angelo. It is also thought that some went to build the bronze canopy over the altar at St. Peter's.

The Pantheon in Rome was the largest concrete construction in existence until the 20th century and the world's largest freestanding dome until the 1960's.

There are a number of tombs in the Pantheon in Rome including one for the artist Raphael and Italy's first two kings, Umberto I and Vittore Emanuele II.

The Pantheon is located in the Piazza della Rotonda which was created under Clement XI, pope from 1700 to 1721. The fountain in the piazza was built by Giacomo della Porta in 1578.

Go to the Pantheon in the morning when it first opens so you can appreciate it in silence without the hustle and bustle of other tourists.  Lay down on your back on one of the benches and look straight up through the oculus.