On the left bank of the Vrbas, in the area of today’s Banja Luka, there was an ancient settlement Castra (from the 2nd to the 6th century). There was a small way station, a military camp and a civilian settlement. There is insufficient evidence of its Medieval existence. In the 16th century, architects built a new fortress there, today’s Kastel, which is among the most beautiful Medieval fortresses in South-Eastern Europe. It developed and extended over time, reaching its final dimensions in the 18th century. In the beginning of the 19th century the importance of the fortress declined, so that by the middle of that century it was somewhat damaged. The last repairs to the fortress were carried out in 1868.