OSROENE. – The Christian province of Osroene was established within its final boundaries rather late, around the middle of the 5th century. Its borders to the east were the course of the Hâbûr from its confluence with the Euphrates to Circesium, and then the course of the Euphrates from Circesium up to the height of Samosata. A region of Aramaic-speaking populations with strong Arab infiltrations, it had quite special characteristics from antiquity: its capital, Orhâi (today Urfa), called Edessa by the Romans (v.), was an important cultural center and, perhaps the most notable place where Syriac became a literary language.
Christianity penetrated the region even before the Peace of the Church, and it developed a series of legends, culminating in the cycle of St. Thomas, whose relics are said to have been brought there around 220, giving it great fame in the East. Meanwhile, the nearby Carrhae (Hârân) remained deeply pagan, preserving its cult until well into the Middle Ages. As for Edessa, documents concerning its religious history—and thus also its Christian monuments—are abundant, beginning with the *Chronicon Edessenum*, compiled from official Church documents. Unfortunately, the abundance of philological data does not correspond to an equal, or even lesser, abundance of archaeological data, since all the churches of the city have disappeared. Many were still seen around 1507 by an anonymous Venetian merchant, whose account was published by Ramusio: “This city was regal, magnificent, and wondrous, as is evident from its ancient monuments and buildings and palaces. There are ten to twelve very large churches, built of marbles of such a kind that I could not express it in words.” Even the Christian epigraphy of the city and of the nearby monastery of St. James (mostly in Syriac), though not poor, does not present significant archaeological data. Thus, one is left with lists of church titles, important for the history of worship but saying nothing about the structure and decoration of these monuments.
The most notable Christian monument of Edessa was the Great Church, which Muslim writers, beginning with al-Muqaddasi, counted among the wonders of the world. Fortunately, a Syriac poetic text, probably composed in the 7th century, provides a fairly extensive and clear description of the form it assumed after the reconstruction by Bishop Amidonius in the Justinianic era. The church was then a domed building of Byzantine rather than Mesopotamian type, probably very similar to another still preserved and well-known building, namely St. Clement of Ankara. The interior of the church was completely devoid of decorative imagery, probably aniconic.
Outside Edessa, there are accounts of churches and monuments that stood in various locations, and the famous monastery of Qenneshrin even has a proper history, edited by Nau. Thus, at Carrhae (Hârân), the existence is known of a church of St. Elpidius and a monastery of Aftonius near the city, and at Constantina (today Virânşehir) it is known that a xenodochium was