The Mamula Fortress is located on the Lastovica Island south of Hercog Novi, near the Lustica peninsula.
The fortress was built in 1853 by order of Austro-Hungarian general Lazar Mamula. Along with the nearby Arza (Lustica peninsula) and Ostro (Prevlaka peninsula, now in Croatia) fortresses, it completely controlled the entrance to the Bay of Kotor.
During World War I the fortress served as a prison. In 1942, during World War II, the island was captured by Benito Mussolini's forces and the fortress was converted into a concentration camp.
The island was deserted for a long time after that, only seeing tourists and a couple of movie shootings. In 2016 the Montenegran government decided to rent out both the island and the fortress. There's current plans to build a premium hotel complex on the island, and tourist access is now restricted.