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. Between these patterns are white and dark red bands, alternating one course of stone with two to five of bricks. This is the first appearance of this most important decorating aspect of the Palaiologian architecture in Constantinople.