#Constantine the Great
- Axiopolis — An ancient Greco-Roman fortress and city, later fortified by the Byzantines, located in Dobruja on the right bank of the Danube, south of modern Cernavodă (opposite Hinog island). Initially founded in the 4th century BC by Lysimachus, king of Thrace, the settlement was structurally rebuilt by Emperor Constantine the Great. It served as a major strategic military and commercial hub, becoming an episcopal seat in the 6th century and a site of martyrdom for Saints Cyril, Quindeus, and Tassius.