Poros Fortress, also known as Burgos, is an ancient and medieval fortress and port city on Cape Foros in Burgas, Bulgaria. Dating to the Late Antiquity and Late Roman periods (4th-6th centuries AD), the fortress and port protected the Roman city of Deultum and controlled strategic waterways between Lake Mandra and the Black Sea. Excavated beginning in 2008, the site revealed numerous buildings, artifacts, and pottery from late antiquity. The fortress remains feature a massive rectangular tower that guarded the main gate and portions of defensive walls measuring 3 meters in width, making it a crucial archaeological site for understanding Roman and Byzantine Black Sea defense networks.