Kastel Fortress is the oldest historical monument in the city of Banja Luka. The oldest evidence of settlements in the area of Banja Luka are the remains of a Neolithic hillfort settlement that has just been discovered in the area of the city Kastel Fortress. Kastel is located in the central part of the city, which dominates the left bank of the Vrbas River. At the site, in addition to the remains of a Neolithic settlement, remains were discovered from the ancient, Slavic and Turkish periods. In the past, Kastel was a strong military fortification and it protected the Vrbas valley from enemy advances. In the medieval Bosnian state, a Vrbas Town existed, which was located where Kastel is today, according to one theory. The fortress, but also the city of Banja Luka, became especially important during the Austro-Hungarian-Turkish wars as an important geo-strategic centre. The fortress is surrounded by thick stone walls from all sides, and its interior holds a national restaurant, as well as a summer stage and playgrounds for children. Today, the Kastel Fortress is the most valuable monument of Banja Luka and a place where you can experience the spirit of past times.