Mar Petyun (Saint Anthony) is a Chaldaean church located in the old walled city of Diyarbakir. It is situated on the north side of the axial east-west street between the center of town and Yeni Kapı. The church is dated to 1830.

The plan of the church is rectangular. Three rows of arcades resting on squat columns and running parallel with the eastern wall divide the interior into a central nave and two side aisles to the north and south. The proportions of the nave and side aisles are the same, all being relatively wide. The central nave ends at a short staircase that leads up to the sanctuary, which is a recession terminating in a pentagonal apse covered by a semidome. Flanking the sanctuary on either side are two recessed niches, both covered by barrel vaults in the form of a pointed arch.

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