Basilica A is in the southern part of Early Christian Nicopolis, southeast of the intersection of two important roads: the main E-W avenue, the decumanus maximus of the Roman urban plan, and a road perpendicular to it (cardo) which ended at the south gate of the Early Christian wall known as the “Beautiful Gate” (Oraia Pyli). It is known as the basilica of the Bishop Dometius (Doumetios) after two bishops of this name who according to metrical inscriptions on their mosaic floors were the founder and dedicator of part of its mosaics, respectively. The Latin name of the bishop, Dometius, is mentioned in the dactylic hexameter inscriptions as Doumetios. As attested by an inscription on the mosaic floor of the atrium’s western portico, the church was dedicated to Saint Demetrius.
The church is a three-aisled, timber-roofed basilica with transept, atrium, and annexes. The main entrance was on the west, with a monumental propylon probably surmounted by a pediment. The main entrance led to the atrium (ύπαιθρον), a type of vestibule for the faithful to gather. It consisted of a central open-air paved area and three surrounding porticos, decorated with mosaic floors. The five-line founder’s inscription on the floor of the west portico mentions both of the bishops Dometius as well as Saint Demetrius.