Of the total 150 Early Christian, Byzantine and Post-Byzantine churches in Athens, 24 have survived virtually intact, 20 remain in a ruinous state, 11 have been disfigured by later intervention, 10 have been replaced by new churches and 85 have been destroyed and no longer exist.
Athenian churches were built of rectangular stones, usually of poros, each boxed in by thin red bricks: this system is known as cloisonne masonry. Bricks were also used to create diverse designs on the exterior, such as letters of the Greek alphabet and of old Arabic script (Cufic). Sometimes they were set diagonally creating rows remeniscent of a saw blade (dentil bands).
Most of the Byzantine churches in Athens are of cross-in-square type with dome. They are of rectangular plan, while on the roof the two vaults intersect to form a cross, at the center of which is the dome of so-called Athenian type, which is small, elegant and usually ocagonal with one or two windows on each side.
These churches are distinguished by their large dome which covers virtually the entire building and rest on eight arches spanning the corresponding eight supports, pillars or pilasters. The supports, as projected on the ground plan of the church form an octagon, within which the circumference of the dome is inscribed (Savior of Lykodemos, Daphni monastery)