Just above the port and below the Hotel Continental, these restored ruins mark the spot where the mighty Fortress of Severin once stood. The fort dates from the 11th century and marked the border between the Hungarian Kingdom and the Bulgarian Empire. It was demolished in the 16th century on the orders of the then-ruling Ottoman Turks. There's not much to see now except a very tall tower and the thick walls of this legendary redoubt.
In its heyday, in the 13th and 14th centuries, it was regarded as the strongest fortress on this part of the Danube.