Basilica D lay atop the low hill of Karaouli with a view overlooking the Ambracian Gulf, outside the walls of Early Christian Nicopolis but within and near the Roman walls and their southeast gate. It was found in the early 1950s during excavations by the Hellenic Telecommunications Organization (OTE) when a wireless antenna was being installed. Its location outside the Christian city and the burials found inside it led to the conclusion that it must have been associated with one of the Christian cemeteries.
Basilica D was three-aisled and timber-roofed, with a projecting tripartite transept, narthex with annexes, and atrium. The expansion of the north and west walls of the atrium beyond its northwest corner attests to the existence of a portico which apparently ensured the main access to the church from the road.
Two doors at the eastern end of the north and south porticos of the atrium led to the narthex, a small part of whose mosaic floor survives. In the center of the floor among geometric designs, a wreath with colorful flowers and fruits held up by a winding band was depicted. This was an extremely common decorative motif in sculpture, but it was rare in the decoration of mosaic floors, an element indicative of the fine and original artistic quality of works by the Nicopolis mosaic workshop.