The fort Kastel is situated in the center of the city, where the Crkvena river flows into the Vrbas. In ancient times there was a road (Servitium-Salona) that was running through the city and connected the then provinces Dalmatia and Pannonia. It is therefore assumed that around the second century A.D there was a Roman military camp castra situated in the territory of today`s Kastel along this route together with a civil settlement. The archaeological findings comprising Roman ceramics, money and ruins are to confirm this. A finding of a particular importance is an antique altar dedicated to Jupiter and found in 1885. The remains of a Slavic settlement from the Early Middle Ages (from the 8th to the 12th century A.D) were also found in the fort surroundings. 
Kastel got its current appearance in the Middle Ages (1580), during the Turkish occupation and the rule of Ferhat-pasha Sokolović (1574-1588), who, apart from this fort, had a whole range of other Oriental facilities built. The fort and the city became a particularly important geo-strategic center during the wars between the Austro-Hungarian Monarchy and the Ottoman Empire. 
Today, the Kastel Fort is a first category monument and a place breathing life into the spirit of ancient times.