The Red Basilica in Bergama is named for the red bricks from which it's constructed. You'll pass it on the road to and from the Acropolis—it's right at the bottom of the hill, in the old part of the city. This was the last pagan temple constructed in Pergamum before Christianity was declared the state religion in the 4th century, when it was converted into a basilica dedicated to St. John. The walls remain, but not the roof. Most interesting are the underground passages, where it is easy to imagine how concealed pagan priests supplied the voices of "spirits" in mystic ceremonies. The main building is fenced off for ongoing restoration, but one of the two towers has been restored and has some displays inside; the other tower is used as a mosque.
Kurtuluş Mh., Kınık Cad., Pergamum, 35700, Turkey