The remains of Diana fortress were found on the high cliff above the Danube in the Karatas Excavation Site. Diana Fortress represents the hugest and best preserved Roman Fortification /castrum/ on the Danube. It was built of stone during the reign of Emperor Traian, probably between 100-101 AD, at the same time when canals were constructed to enhance sailing along the Danube. Diana Fortress has rectangle shape of dimensions 100 cross 200 meters with towers on the walls.

The finalization of building was at the end of the 3rd century and the beginning of the 4th century AD when towers were added towards the river, protecting the shore of the Danube. At the middle of the 5th century Diana Fortress was destroyed by the Huns and in 530 AD was rebuilt by Emperor Iustinian. The military camps with related objects were found beside the Diana walls and the entrance gate with towers and the sacrificial necropolis and small settlement above the walls. Significant archaeological artifacts /various daily tools, marble and bronze sculptures /were found. They are the evidences of the great economic importance of the port of Diana fortress, as well as its strategic and defensive role on the Danube line in Roman times. In 1983, Diana Fortress was added to the Archaeological Sites of Exceptional Importance list, protected by Republic of Serbia.