Trebinje (Cyrillic: Требиње) is the southern-most municipality and town in Republika Srpska, Bosnia and Herzegovina. It is located in southeastern Herzegovina , some 10km from the Adriatic Sea.
The toponym Trebinje comes from a medieval term Travunia. Trebinje was probably built by Slavs on the site of a Roman town laid waste by the Saracens in 840. In the mid-10th century Constantine Porphyrogenitus mentioned it under the name of Terbunia. It commanded the road from Ragusa to Constantinople, traversed, in 1096, by Raymond of Toulouse and his crusaders. Under the name of Tribunia or Travunja (the Trebigne of the Ragusans), it belonged to the Serbian Empire until 1355.
The town lies on the Trebišnjica River in Southeastern Herzegovina, some 24km by road from the city of Dubrovnik (Croatia) on the Adriatic Sea. There are several mills along the river, as well as several bridges, including 2 in Trebinje itself, and a historic Ottoman Arslanagic bridge nearby. The river is heavily exploited for hydro-energy. After it passees through the Popovo polje area (South-West of the town), which always floods in winter, it naturally runs underground to the Adriatic Sea, near Dubrovnik in Croatia.
There is an Orthodox church in Trebinje, Saborna Crkva, as well as a new monastery, Trebinje Gracanica, located above the town, on the historic hill known as Crkvina, while nearby is also (what is now an Episcopal church) Tvrdoš Monastery, dating back to the 15th century. Trebinje is also home to the Catholic Cathedral of the Birth of Mary. The Osman-Pasha (Resulbegovic) Mosque is in center of Trebinje.