When Olympian worship effectively ended, the Pantheon essentially stood idle for a couple hundred years, before being used as a church again. Indeed this pagan building has been a Christian (Catholic) church for most of its history.

It's also famous in the history of the Renaissance because builders of two famous, domes, Brunelleschi (who built the dome in the Duomo in Florence) and Michelangelo (who designed the dome of St. Peters in the Vatican City) both studied the dome.

And the dome is indeed the overwhelming feature of the place, large, strangely graceful despite being made of essentially ancient concrete, it rises large and far above you. We were there in mid afternoon, and light streamed through the dome down into the building itself. It is open to the world and yes, when it rains, it just rains in.

Columns remain from the original construction, in remarkably good condition (the entire place is in incredible condition for a building that is close to 1900 years old). Most of the interior decoration, particularly sculpture, is Christian in nature, although you can see where the statues of the Olympian Gods would have been.

When we visited they were saying mass. This does not preclude visiting, though it limits where you can walk significantly. One needs to remember that this is indeed a church. As we were visiting as pilgrims, it did feel a little intrusive to enter as viewers, but while we were in there an unseen choir burst into a beautiful rendition of Mozart's "Ave Verum Corpus" which resonated off the stone and the dome and filled the place with great spiritual beauty. With the sunlight filtering through the ceiling, the candles flickering soundlessly and the heavenly statuses around us, it felt like a true moment of worship.

Most tourists tend to bypass the exterior of the Pantheon and rush right in to be dazzled by the spectacular dome. True, the outside of the building doesn’t hold quite the mystique and splendor found within, but a little study of it is necessary to appreciate this fine gem of the Ancient World. When facing the portico, visitors may notice a bit of a wall behind the triangular pediment. This is not a structural support or decorative feature of any kind, but rather an everlasting reminder of a wee mistake made in the measuring department. That pediment was actually supposed to grace the top of this wall, but when the columns arrived from the contractor, they were much shorter than requested. Hmmm, perhaps those responsible were thrown to the lions? From the portico, tourists should walk around the side of the building towards the "drum" which supports the dome. These walls are 19 feet thick and reinforced with hidden pillars and weight relieving arches. Visitors will find these embedded brick arches towards the top of the drum, above the little windows.

Upon entering through the ancient bronze door, tourists seemingly step into the past. In constant use since it’s construction, the Pantheon is Rome’s most well preserved ancient site. It’s not at all hard to imagine what this place must have been like in ancient times. The only real changes made since those days are the saint statues that now grace the niches where pagan gods once stood and a few tombs of famous people.

The dome of the Pantheon, the largest created up until the Renaissance, sits atop its circular pedestal like a great eye focused on the heavens. It is equal in height as well as diameter (140 feet) with an oculus spanning about 30 feet across. The dome was cast by pouring concrete mixed with different types of volcanic rock over a temporary wooden framework. As a result, the dome gets lighter and thinner towards the top. The hollow, decorative squares incorporated into the design also help to reduce the weight significantly. Perhaps the most architecturally influential building in all the world, this site has played a large role in the inspiration and design of many famous landmarks. Buildings like the Florence cathedral, Saint Peter’s, the US Capitol and even Arlington Cemetery all share definite characteristics first created here.

No admission fee is charged for the Pantheon and it’s open Monday through Saturday from 8:30am to 7:30pm and again on Sunday from 9am to 6pm. Remember, this site is now considered a church, so "modest dress" is required.