The fortress is medieval but is situated on the site of previous fortifications going back to Roman and even pre-Roman times.

The fortress is relatively well-preserved, and is one of Banja Luka's main attractions, situated on the left bank of the Vrbas river in the very center of town.

It is made using the technique of reduction firing ceramics, giving it a burnt, black and grey finish.

The similarities of the Vinča and Starčevo culture display themselves in their techniques of fine polishing the outer surfaces of dishes and containers.

The fact that the technique of white encrustation followed the spread of metallurgy implies the connection between the symbols of Vestal virgins as firekeepers and the ritual sacrifice of children before building melting ovens.

The appearance of white encrusting, in the mythical version, according to which Prometheus carried over the stolen flame to humans, has its own link with the plant by the name of Ferula Communis, which sprouts all across Mediterranean.

In the middle of the XVII century in Banja Luka, in the itinerary of Evlija Čelebija, and also some other travelers, two towns are mentioned.

The name "Banja Luka" is first mentioned in 1494 in one document issued by the Hungarian king Ladislav II Jagelović.

In the war between the Habsburg and Ottoman empire (1683-1699), Austrian troops, under the command of count Ludwig of Baden, shortly occupied Banja Luka on August of 1688.

In 1528, the entire territory of Jajačka banovina, from Jajce to the river Sava, fell to the Ottoman rule.

The first Beglerbeg (ruler) was Gazi Ferhad Pasha Sokolović, who initiated substantial building activity in the Lower Šeher, today's center of the city, where he built 216 objects.

Kastel is an artillery fort situated on the plains and it has a polygonal foundation in the shape of an extended trapezoid.

The fort was built out of rectangular chiseled stone, set upon each other in variety of ways and tied together with mortar.

It was about 20-30 meters wide and it surrounded Kastel from all sides, except alongside Vrbas, making it almost seem like the fort was on an island.