The foundations of Ardashir at Firuzabad

One area to focus on is a cluster of three sites built by the first king, Ardashir I. The first of these is a fortified palace called Qaleh-e Dokhtar, built on a high bluff, which overlooks the river and roadway running south from Fars. The entrance to the castle is through a tall gateway in a large, rectangular tower.
Inside this a broad stairway leads up to a rectangular hall, with blind niches on either side and two large buttresses at the east end.
These supported stairways up to the next level, another large rectangular room, 14 x 23 m, with an arched recess, an iwan, at the east end and arched blind windows on either side.
It was presumably roofed by an arched vault. Beyond this there are steps to a third level and a large rectangular room with ¼ circle squinches at each corner supporting a domed roof. This was buttressed by very thick walls on all sides, presumably to ensure its stability, and the cupola could be reached by a spiral staircase on the south side. This splendidly coherent and confident building contains many of the recurring features of Sassanian palace and civic architecture: long halls, arches, domes, recessed windows, stairways. The construction is uniform of roughly shaped stone and mortar, but the surfaces were obviously all finished with a thick coating of plaster or stucco, giving a smooth and elegant appearance, which could have been decorated with ornamentation or painting.