Some 4km northeast of Kızkalesi and just off the D400 are the extensive remains of ancient Elaiussa Sebaste, a city dating back to the early Roman period and perhaps even to the time of the Hittites. Important structures on the western side of the D400 include a 2300-seat hilltop theatre, the remains of a 2nd-century Byzantine basilica and Roman agora with fabulous fish and dolphin mosaics, and a total-immersion cruciform-shaped baptistery.
The ruins of a 5th-century Byzantine palace are on the eastern side of the highway. It was abandoned during the Arab attacks of the 7th century.