They are often covered with carved stucco reliefs, some of the finest examples of which are found at Uruk and Ashur. The palace at Ashur has the earliest example of four iwans opening onto a central square. This form of architecture supplants Hellenistic styles in Iraq and Iran, and will play an important role in the religious architecture of the later Islamic period. A new fashion, frontality, arises in relief sculpture where the head and body are shown frontally. His successors establish their administrative and economic center at Ctesiphon.
Buildings continue to be embellished with stucco, now largely molded rather than carved.
The moldings, applied like tiles to walls, create repetitive friezes that depict figural, animal, geometric, and floral motifs. Despite constant aggression between the Sasanians and Byzantium, there are parallels in the arts, especially motifs on textiles that reflect mutual differences. The use of frontality, introduced in the Parthian period, continues in Sasanian art, and becomes a hallmark of the Romano-Byzantine West. A new era is ushered in when the Sasanian empire falls to Arab forces at the battle of Nehavand in southwestern Mesopotamia, leading to the rapid unification of the Near East under the banner of Islam. The Metropolitan Museum of Art.