The building lies on a slope which overlooks the Golden Horn, and rests on a platform which is the ceiling of a cistern. It is closely hemmed in all sides, making an adequate view of the exterior difficult. Its masonry consists of brick and stone, and uses the technique of "recessed brick"; it is the oldest extant building of Constantinople where this technique can be observed, which is typical of the Byzantine architecture of the middle empire. In this technique, alternate courses of bricks are mounted behind the line of the wall, and are plunged in a mortar bed. Due to that, the thickness of the mortar layers is about three times greater than that of the brick layers. The brick tiles on its roof are unique among the churches and mosques of Istanbul, which are otherwise covered with lead.