It is known that the Underground Church was built in the 4th century, and the ruins in the upper part were built in the second half of the 5th century A.D. It is the 4/1 part of the church apse that survives today. It is known that this basilica-planned building was built on the site of a small church that was located here before. It is 80 meters long and 36.80 meters wide. The church has 15 columns, and 3 naves, and its floor is furnished with black, white, and red tesserae in Opus Sectile style. The Votive Church, located 150 meters northeast of the present cistern, was built by Emperor Zenon between 476 and 491 A.D as an offering to St. Thekla. There was a bathing structure between the Votive Church and the Small Church. On both sides of the narrow Bosphorus, there is a cemetery that was used as a martyrdom in the 6th century A.D. The cistern with a length of 14.40 and a width of 11.10, located to the east of the basilica, is dated to the first half of the 6th century.