The basic building material of the citadel was brick and not stone. The citadel is a brick town and it may be strongly claimed that brick was its very essence. This beautiful yellow-ochre material was used for almost everything- walls, vaults, arches, columns, floors, and decoration. Brick kilns (Kooras) were located outside the citadel town and used local earth quarries for manufacturing different types and sizes of bricks.
Basically, bricks came in two types- one for building load-bearing walls and the other for paving floors and other surfaces. Structural bricks came in several sizes but commonly they were about 20 x 10 x 5 centimeters. Paving bricks, on the other hand, were about 28 x 28 x 5 centimeters. Bricklayers of the citadel were extremely skilled craftsmen and this can be attested by the many ingenious ways they handled this material. One may truly admire, for example, the brick patterns they used in vaulting semi-basements, or the many different combinations of brick patterns they employed for roof parapets.