The Alahan Monastery (turkish Alahan Manastırı) is an early Byzantine ruin, 11 km north of Mut and 2 km above the D715, the road from Silifke to Karaman. Due to its location at an altitude of 1200 m with a magnificent view over the valley of the Kalykadnos and the good preservation of its buildings, it is one of the most impressive ancient sites of Asia Minor.

A 130 m long portico leads to the main church in the far east, an almost completely preserved domed church (except for the missing roof).

The ancient name of the place is not known. The village below the church is called Alaca Han (The Multicolored Han) by travellers at the beginning of the 19th century. At the end of the 19th century the village was called Koca Kalesi. Since the middle of the 20th century the common name is Alahan Manastırı (Monastery Alahan).

In Alahan, a whole complex of connected buildings from the end of the fifth century has survived. To the far west are the remains of the Evangelist basilica, once with three naves, which replaced a previous building from the fourth century.

Little is preserved of narthex, but the frame of the portal, which consists of three monolithic blocks and is richly decorated with acanthus reliefs and figurative motifs. Two floating angels hold a Christ medallion on the lintel. On its underside is a creature with four wings and four heads, on the inside of the pillars the archangels Gabriel and Michael.

Baptismal font in the Baptistery

Further east are the remains of a two-aisled baptistery with a Byzantine cross as a font.

In the late 17th century, a traveller described the complex as "a building recently handed over by the architect".British archaeologist Michael Gough began his research and excavations here in 1952, which came to an end with his death in 1973.
From 2002 to 2006 further research took place in Alahan and its surroundings.