Alahan Monastery (mid-twentieth-century name) known locally as Koja Kalesi in modern Mersin Province is a fifth century ecclesiastical complex that dominates Calycadnus valley (Göksu) in ancient Isauria (Cilicia Trachea). It was erected in the mid-fifth century AD under Emperor Leo I and later expanded in the last quarter of the fifth century AD during the reign of Emperor Zeno. It consists of the Western Church, the Monastery, the Eastern Church, the monks' chambers carved into the rocks and the surrounding tombs. Church buildings have common architectural features with Hagia Sophia.
See:
- Michael Gough, Some Recent Finds at Alahan (Koja Kalessi), Anatolian Studies, Vol. 5, (1955), p. 115
- http://tayproject.org/TAYBizansMar.fm$Retrieve?YerlesmeNo=20537&html=bizansdetaile.html&layout=web