The building is topped by an Ottoman dome pierced by eight windows. This edifice has three high apses: the central one is polygonal, and is flanked by the other two, which served as "pastophoria": "prothesis" and "diakonikon". The apses are interrupted by triple (by the central one)and single lancet windows. The walls of the central arms of the "naos" cross have two orders of windows: the lower order has triple lancet windows, the higher semicircular windows. Two long "parekklesia", each one ended by a low apse, flanks the "presbytery" of the "naos". The angular and central bays are very slender. At the four edges of the building are four small roof chapels, each surmounted by a cupola. The remainders of the original decoration of this church are the bases of three of the four columns of the central bay, and many original decorating elements, which survive on the pillars of the windows and on the frame of the dome. The decoration consisted originally in marble panels and coloured tiles: the vaults were decorated with mosaic. Only spurs of it are now visible. As a whole, the north church presents strong analogies with the Bodrum Mosque (the church of "Myrelaion"). The "south church" is a square room surmounted by a dome, and surrounded by two "deambulatoria", an "esonarthex" and a "parekklesion" (added later). The north deambulatorium is the south parekklesion of the north church. This multiplication of spaces around the central part of the church is typical of the late Palaiologian architecture: the reason of that was the need for more space for tombs, monuments erected to benefactors of the church, etc. The central room is divided from the aisles by a triple arcade. During the mass the believers were confined in the deambulatoria, which were shallow and dark, and could barely see what happened in the central part of the church. The masonry is composed of alternated courses of bricks and stone, typical of the late Byzantine architecture in Constantinople. The lush decoration of the south and of the main apses (the latter is heptagonal), is made of a triple order of niches, the middle order being alternated with triple windows. The bricks are arranged to form patterns like arches, hooks, Greek frets, sun crosses, swastikas and fans.