The ancient city of Rusafa is located in eastern Syria south of the Euphrates River, toward the western fringe of the steppe lands that stretch from Iran in the east to the agricultural hinterlands of Aleppo in the west. Diocletian (r. 285-305) established Rusafa as permanent fortified enclosure on the border of the Roman Empire and Sasanian Iran, although the site is mentioned in earlier biblical and Assyrian texts. Its transformation into a permanent settlement may have to do with its strategic location on the borderlands of the two great empires of late antiquity, situated both along overland routes from Syria into Mesopotamia and located near watering sites in the arid steppe.1 

Rusafa flourished from the fifth through the seventh century AD during which time the relics of Saint Sergius were translated to a new shrine within the city walls, attracting pilgrims. The city was renamed Sergiopolis after the martyr saint and grew to prominence as a pilgrimage center. In the seventh century, the Umayyad caliph Hisham ibn 'Abd al-Malik (r. 724-743) moved his residence to the site, renaming it again Rusafat Hisham and adding further to its importance. The city remained a pilgrimage center until it was destroyed by the Mongols in 1259/657 AH. Excavations of the site were undertaken by the Deutsches Archäologisches Institut beginning in 1952 and have added greatly to our knowledge of the histories of the various buildings found there.

The city is laid out in an irregular rectangle, approximately 550 m x 400 m. The remnants of civic, religious and residential structures have been identified at the site by surveyors and archaeologists, and aerial photography suggests traces of gardens, indicating that the city would have been a veritable oasis in its heyday. Indeed, the Spanish Umayyad caliph 'Abd al-Rahman I is famed to have wistfully remembered the gardens of Rusafa in a poem he wrote from his exile in Andalus, and even named an agricultural villa (munya) in his new Andalusian home after the Syrian city.

City walls enclose the site, with fifty half-round, square and polygonal towers, four main gates, and two smaller gates. The largest and most elaborate of the city gates is the northern gate, which is decorated with architectural sculpture related to styles seen in other northern Mesopotamian cities like Nisibis and Mardin.2 Evidence suggests that the city had several main streets, one leading from the northern gate that was lined with arcades and shops and intersected and east-west running street in an open square.

Three religious structures have been identified within the city. First, there is the large complex known as Basilica A constructed in the late fifth century and modified thereafter. This church was formerly identified as the Church of the Holy Cross but this identification has since been called into question based on new evidence. Second is an early sixth century church dedicated to Saint Sergius known as Basilica B. Third is a church with a tetraconch plan originally identified as a martyrium but whose specific function is unclear. Civic structures in addition to the streets, shops and squares include three cisterns. Finally, an audience hall attributed to the Ghassanid chieftain al-Mundhir III ibn al-Harith was constructed in the second half of the 6th century outside the city walls. 

1. Fowden, Barbarian Plain, 67-77.

2. Guyer, "Rusafa," 16-28.

Sources:

Beattie, Andrew, and Timothy Pepper. Syria: the rough guide, 258-261. London: Rough Guides, 2001.

Burns, Ross. Monuments of Syria : an historical guide, 203-206. New York: I.B Tauris & Co., 1992.

Fowden, Elizabeth Key. The Barbarian Plain: Saint Sergius between Rome and Iran. Berkeley: University of California Press, 1999.

Guyer, Samuel. "Ruṣāfah." In Archäologische Reise im Euphrat- und Tigris-Gebiet. Edited by Friedrich Sarre and Ernst Herzfeld. Volume 2, pp. 1-45. Berlin: D. Reimer, 1920.

Ulbert, Thilo. "Rusafa." Grove Art Online. Oxford Art Online. Oxford University Press, accessed September 16, 2015, http://www.oxfordartonline.com/subscriber/article/grove/art/T074511.