Ostrvica or Ostrovica was a small town in the Principality, perched on a domineering 800-meter high cliff about 5 km away from Mt Rudnik. The steep sides of the cliff potected the town from all sides.

Ostrvica consisted from two parts: big and small town. Initially built on separate rocks, they were subsequently connected by a wall. The only remnants of the entire fortification are parts of the small town and a larger part of the wall surrounding the top of the cliff where the big town used to stand.
The fortification, which has always been an attractive sight for passers-by, offered a good shelter to people in plight. Some believe that the town was built in the ancient times. However, it was first mentioned in the 14th century, when Dubrovnik merchants hid there from the ravages of war. Old Serbian chronicles registered that the Ottomans had seized and demolished Ostrvica on two occasions – in 1348 and in 1454, when the Sultan ordered its complete destruction.

Ostrvica is most frequently visited by holiday-makers, mountaineers and school excursions.