Fortress Kostajnica is a castle in Hrvatska Kostajnica, a town in central Croatia, near the border to Bosnia and Herzegovina.
The fortress was built most probably in the 14th century and owned by the members of the noble families Frankopan, Lipovečki, Tot, Benvenjud and finally Zrinski, so it is today also known as „Zrinski fortress“ or „Zrinski castle“. It was conquered by the Ottomans on 17 July 1556, but it was freed from their rule relatively fast, in 1688.
Situated on the bank of the river Una, the fortress has very strong walls and three towers. Having been in pretty bad shape before, it has been renewed in the recent years by the Croatian Ministry of culture.
Address 5 Ulica Krešimira Hajdića, 44430, Croatia
Coordinates 45°13'16" N 16°32'49.999" E