When I was in Perugia in September, I spent a few hours in and around the Chiesa di Sant'Angelo, a very cool little church that is believed to be one of the oldest in Perugia. It was built in the 5th century, likely on top of the remains of a Roman temple, during the last days of paganism.
The early Christian church of Sant'Angelo is also called the Tempio di San Michele Arcangelo.
According to BellaUmbria, it has typically Roman characteristics. The two inner areas, the ambulatory and the central presbytery, are separated by a circle of sixteen Corinthian-Roman columns.
Given their variety of measures and materials, they were probably carried into the church from another building, as was customary at the time. The two adjacent chapels at the church's external sides give it a Greek cross layout.
I took the above photo of Sant'Angelo from high atop the adjacent Porta Sant'Angelo, the largest of Perugia's medieval gates which was re-built in 1326. Its tower has been beautifully restored (more recently, of course) and now houses the Museo delle Mura e delle Porte di Perugia -- the city's museum of historic walls and doors. Etruscan and medieval models, that is, and pretty interesting. That's it, in my photo below. The viewing area is at the very top of the tower.
This museum gives a fascinating look at the history of the city, and from the top of the tower, the views are fantastic!
Still, I'm especially partial to the round Chiesa di Sant'Angelo down below and on this trip, was able to finally get inside for a good look around.
I like this description of the unusual church, from BellaUmbria:
"Those who love mystery and go to Perugia cannot but visit this church. In effect, there are very strange symbols inside. On the doorjambs and on the neck of the Virgin Mary depicted in on of the frescoes some crosses representing the mystic universe of the Templars, a medieval religious confraternity whose legendary history is full of secrets and enigmas.
"Moreover, at a few metres from the entrance there is a pentagram, namely a symbol linked to the worship of Venus associated to black magic in the Middle Ages."