Brick was the principal building material in the walls and vaults of many Byzantine churches.
Byzantine builders commonly used brick masonry, often combined with mortar and occasional stone courses. Brick was practical for constructing curved surfaces such as arches, vaults, and domes, and it was widely available around Constantinople and other major centers.
Exterior brickwork could be left visible or covered with plaster, while interiors were enriched with marble revetment, mosaics, frescoes, and painted decoration. This contrast is why visitors may associate Byzantine churches more strongly with marble and mosaic than with brick.
Construction varied by region and period. Stone, reused Roman material, and other local resources were also important, so brick was predominant in many examples rather than universal in every Byzantine building.