Skeleton of of a suspected Roman ship was found in coal quarry.
The Roman city of Viminacium was a major military camp and the capital of Moesia Superior (today’s Serbia).
According to the Roman document Notitia Dignitatum, part of the Danube fleet was anchored at Viminacium. The veracity of the claims, however, were long debated since the city is not near any modern waterway.
The finding of a suspected 3rd or 4th century AD Roman water-ship in a large coal quarry at least supports the idea that the Danube was either flowing farther south than it does today or a major branch of the river was near the city.
https://greekreporter.com/2023/08/04/ancient-roman-ship-serbia/