Archaeologists in southeastern Türkiye have determined that a subterranean temple dedicated to the ancient Roman-era belief system of Mithraism at Zerzevan Castle in Diyarbakır was sealed and closed about 1,700 years ago, likely after the spread of Christianity in the region.
The discovery comes from ongoing excavations at the 3,000-year-old fortress, which served as a Roman military settlement. The site sits on a 124-meter-high (407 feet) rocky hill near Demirölçek in the Çınar district, about 13 kilometers (8 miles) from the district center. Researchers say Zerzevan Castle contains the world’s last known Mithraic temple uncovered within a military complex.
Excavations began in 2014 and the site was added to the UNESCO World Heritage Tentative List in 2020.
Archaeologists have uncovered extensive remains across roughly 1,000 acres, including 15-meter-high (49.2 feet) defensive walls stretching 1,200 meters (0.75 miles), a 21-meter (69 feet) watchtower, a church, administrative buildings, residences, grain and weapons storage facilities, rock-cut tombs, water channels and 63 cisterns. The complex also includes an underground church, a 400-person underground shelter, hidden passages and a Mithraic sanctuary used for secret religious rituals.
