The so-called Red Church at Sivrihisar is well known and has long been associated with Gregory of Nazianzos and his estate at Arianzos. Situated in a high mountain valley above Karbala (Güzelyurt) in western Cappadocia, the church actually dates from the sixth century (and is thus too late for Gregory) and was known to the 19th century Greeks of the area as St. Panteleimon. Nevertheless, it is usually discussed as an example of a memorial church. Oddly, the architectural features of the surviving building have received considerably less attention than its alleged origin or function. The best preserved of the Byzantine masonry churches of central Anatolia, the Red Church is unique in the survival of its dome – perhaps the earliest known example of a dome rising above a tall, windowed drum. This paper will examine the structural system of the building focusing on the unique solutions developed by its masons to address the outward thrusts of the dome and barrel vaults. I will also touch upon several unusual details of design and construction preserved in the building’s fabric.