The Greek Orthodox church of Sts. Constantine and Helen stands in the centre of Derinkuyu as a remnant of the town's substantial Greek-speaking Christian community, which was expelled during the 1923 population exchange between Greece and Turkey. The building dates from the 19th century and is now used as a mosque, though its original character — the arched nave, the carved stonework — is largely intact.
It is a quieter and less-visited sight than the underground city, and all the more interesting for that. The contrast between this above-ground church and the subterranean Christian spaces beneath the town makes the broader history of the community tangible in a way that the underground city alone does not.