Parthian Architecture and Building

From 247 BCE to AD 224, the Arsacids, the Parthian royal dynasty, ruled parts of a wide region where builders adapted local materials for royal, sacred, civic and domestic needs. The royal complex at Old Nisa in Central Asia, houses at Susa in southwest Iran and the sanctuary at Hatra in northern Iraq reflect different patrons and regional building practices. Hatra was a local kingdom whose dynasts were subordinate to the Arsacid king of kings, while Old Nisa was an Arsacid royal center. These projects drew on long-established regional traditions.

Materials and building phases

Across Iran, builders traditionally made mud bricks from water-soaked earth mixed with straw and chaff, shaped in wooden moulds and dried in the sun. At Old Nisa, near modern Ashgabat in Turkmenistan, the surviving buildings have mud-brick walls and stand on a raised platform. Timber columns divided roof spans so beams could cross them, while plaster covered interior walls. The Square Hall stood on a platform formed by filling earlier structures. In a later phase, builders replaced its four central supports with massive four-lobed fired-brick piers, broad masonry supports. These piers could have supported a lantern roof, an elevated roof section that admits light. The new supports changed how the building bore weight while it retained its raised base.

A separate building, the Square House at Old Nisa, included reception and ceremonial spaces as well as store rooms. Archaeologists suggest that the Square House first served for official assembly and banqueting, then became a store for precious furnishings, weapons, ceramics and coins, probably from around the first century CE. Long benches lined its rooms, and rows of wooden columns carried their roofs. As rooms filled, builders partitioned them and added store rooms in the former portico, a covered walkway beside the court, eventually blocking the entrance. Painted surfaces and sculpture gave important interiors a more formal finish.

Courtyards, houses and vaulted halls

Courtyards brought daylight into deep buildings and connected rooms with different functions. Parthian-period houses at Susa, in southwest Iran, centered on courts, with rooms around them, a larger room on the south side and an upper floor. Excavated residential areas included a particularly large second-century house. After Elymaean rule from neighboring Elymais, Susa returned to Parthian control in 215 CE; its houses continued to organize rooms around courts. The residential buildings present a domestic scale distinct from the royal complex at Nisa.

An iwan is a rectangular roofed hall open at one end, usually facing a courtyard. At Seleucia-on-Tigris in modern Iraq, late first-century CE houses shifted from a reception hall with paired columns at its courtyard opening to a main room roofed by a brick barrel vault. A barrel vault is a continuous arched ceiling shaped like a half-cylinder. The room plan changed little, but the taller vault emphasized its length and made the reception space more imposing. Because a vault presses outward as well as downward, builders used parallel side walls and flanking corridors to brace it. The technique was older: brick barrel vaults had been used at Susa long before. What changed at Seleucia was their use as the main roof over an open-ended reception room.

At Hatra, in modern Iraq, two near-circular fortification lines enclosed a trading city whose main wall had four gates and defensive towers. Within the city, a walled sanctuary court held temples rather than a royal palace. Dated inscriptions place the Great Temple and its open-fronted vaulted halls in the early second century CE. The local builders quarried stone at nearby sites: massive rough-stone walls were faced with cut blocks around entrances and arches. At the back of the smaller court, eight high, barrel-vaulted iwans formed a façade 115 meters long. Its stone construction differed from the brick vaults of Seleucia and the earthen buildings of Nisa.

Decoration and later development

Plaster could cover brick walls, mask unevenness and provide a surface for carving or painting. Painted surfaces and sculpture enriched important interiors.

After AD 224, related forms continued and changed under Sasanian rulers. The great vault at Ctesiphon and royal buildings at Firuzabad belong to this later development, not to surviving Arsacid construction.