Sassanid Architecture and Building

The Sasanian Empire ruled from 224 to 651 CE, with major building projects in Iran and Mesopotamia. Its builders used mud brick, rubble stone, fired brick and gypsum mortar in ways shaped by the material at hand and the space required. A palace audience hall, a religious sanctuary and a planned town each posed different architectural problems, but vaulted masonry linked many of them.

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Materials and the work of building

Mud brick and mortar masonry both had earlier histories, but under the Sasanians they became central to monumental building. Mud brick remained a major material, especially where earth was available close to a site. Because it weathers more readily than stone, many mud-brick structures have disappeared, leaving stone and fired-brick monuments more visible in the archaeological record. Rubble stone set in gypsum mortar was common in surviving walls. Fired brick was often chosen for vaults and domes, while precisely cut stone appeared in selected places and periods.

Gypsum mortar helped builders roof rectangular halls with barrel vaults, long curved roofs shaped like the inside of a half-cylinder. The mortar set quickly, allowing a bricklayer to lay pitched courses without building a complete centering structure beneath the whole roof. The first courses leaned against a rear wall or a small temporary support called centering. Each following course was angled so it rested against the one already in place. As the gypsum hardened, the rows formed a continuous vault. The roof’s weight pressed down and outward, so thick walls and adjoining vaulted rooms helped hold it in position.

Sasanian builders often used pitched courses for barrel vaults; when they built a semicircular arch from horizontal courses, centering supported the bricks until the arch held. A series of vaulted bays could extend a rectangular room or surround a larger chamber.

Iwans and royal reception halls

An iwan is a rectangular vaulted hall open along one side. Its open face turned an interior into an approach from a court, while the deep roofed space sheltered an audience or reception. At the early Sasanian palaces near Firuzabad in Fars, southwestern Iran, founded by Ardashir I, the iwan and a domed hall formed the public reception suite. Side rooms connected to the hall, and subsidiary rooms behind the reception area could serve other palace activities.

At the great palace on the plain, Ardashir I’s throne stood in the wall between the iwan and the central domed hall. The king could receive a smaller group in one space or address a larger gathering in the other. High windows on an upper floor looked down into the ceremonial halls; more private living rooms lay above and between the roofed spaces. The plan therefore arranged both what visitors saw and how the court could observe a gathering.

Centuries later in the dynasty, the great iwan at Ctesiphon, near the Tigris in present-day Iraq, made the vaulted entrance itself the dominant feature. The standing Taq Kasra is the remains of a royal audience hall. It is commonly associated with the reign of Sasanian king Khosrow I, though its precise date remains debated. Unlike the Firuzabad palaces, its iwan does not lead into a domed hall; the plan and the use of the roof shifted over time.

Domes over square rooms

A dome curves over a circular or polygonal space, while many Sasanian reception rooms began as squares. Builders joined those shapes with squinches, arches built across the upper corners of a square room. A set of squinches turned the square into an intermediate many-sided base from which the dome could rise. This corner transition carried the roof’s load into the thick walls below.

The palaces at Firuzabad, including Qalʿa-ye Doḵtar and Ardashir’s later palace on the plain, show domes above square halls. Their early squinches are built from rubble masonry and do not form a perfect circle, but the transition already allowed a domed chamber to sit over a square plan. A four-arched domed chamber is called a chahar-taq. The name describes its form; builders also used four-arched spaces within larger compounds, so the plan alone does not establish that a building was a fire sanctuary.

Sanctuaries and churches

Sasanian fire sanctuaries did not all follow one layout. Some may have used a free-standing four-arched dome over the sacred fire during worship; excavated plans also show enclosed chambers where priests maintained the fire, with adjoining passages and rooms. At Takht-e Soleyman, a sanctuary in northwestern Iran, historical traditions and small clay seals bearing priests’ names and titles support its identification as the shrine of Adur Gushnasp, one of the major royal fires. The Sasanian sanctuary phase is tentatively dated to the sixth century.

Christian communities also built churches within Sasanian territory. Excavated churches at Hira, a Mesopotamian city, and Ctesiphon used long prayer halls with two rows of pillars and a three-part choir at one end. The long hall gave a congregation space to gather, while pillars divided the interior into aisles and the choir, the area reserved for clergy, marked a distinct place for worship. These plans show how religious buildings adapted masonry and interior divisions to different ceremonies.

City plans and water

Sasanian towns followed more than one plan. Ardashir I’s foundation of Gōr, later called Firuzabad, was a circle about two kilometres across, divided into twenty sectors by radial and concentric streets. A wall, ditch and four principal gates defined the settlement and its approaches. Water canals fed from springs and a tunnel cut through a ridge supplied the plain, linking city planning to irrigation and the needs of the surrounding landscape.

By contrast, Bishapur, founded by Shapur I in Fars, used a rectangular, right-angled street plan with two main axes meeting at a central commemorative monument. Most cities continued older settlements whose streets had grown over time rather than following a new geometric plan. Domestic layouts and living conditions are discussed in the article on ordinary buildings.