Kastel Fortress
Banja Luka, Bosnia and Herzegovina
The Kastel Fortress (Serbian Cyrillic, Tvrđava Kastel) is a fortress located in Banja Luka, Bosnia and Herzegovina. The fortress is medieval but is situated on the site of previous fortifications going back to Roman and even pre-Roman times. It was captured by the Ottoman Empire in 1527. 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.
Fort data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).