The fate of Christianity during the first centuries of Islamic era can be observed through the archaeological study of two buildings that may belong to the Church but are not places of worship. The first building is the so-called “Palace of Trajan”, the possible residence in Bostra/Bosra of the metropolitan archbishop of the Provincia Arabia; the second one is a hypothetical charitable hospice in Umm es-Surab, an ancient village of the same Province. They were built during the late 5th or 6th century CE and inhabited until the mid of the 8th century. In both of them, archaeological research has been conducted that provides clues on the probable Christian identity of their occupants at the end of the Umayyad era, as well as the possibility that they have retained their original functions still at that time.