Gradačac Castle, Fortress in Gradačac, Bosnia and Herzegovina

Gradačac Castle is a fortified complex on a hill above the town centre, at about 138 metres above sea level on the slopes of the Majevica range. Its curtain walls reach around 18 metres in height and enclose the upper hill, while a three-storey tower rises to about 22 metres. The tower and a lower konak are joined by a shared wall, and the tower's walls are 1 metre thick.

The fortress was built between 1765 and 1821 and became closely linked to Husein Kapetan Gradaščević, who led a resistance movement in the early 1800s. This period shaped the stronghold's importance in regional history.

The castle is the seat of the Gradačac captaincy, and its tower is remembered as the headquarters of Husein-kapetan Gradaščević, called "Zmaj od Bosne" (Dragon of Bosnia), who in 1831 led Bosnian ayans against the sultan's centralising reforms. The nearby Husejnija mosque and clock tower stand outside the walls, not inside them. The tower now holds a restaurant serving traditional Bosnian dishes.

Visitors can explore the complex during regular opening hours, with guided tours available throughout the site. A restaurant on the grounds serves regional food and provides a place to rest while visiting.

The tower's walls are 1 m thick, and inside the konak they are as thick as the outer walls, which suggests the tower already stood as part of an earlier defensive system before the konak was added. The whole complex measures 15.50 x 12.50 m, with the tower's base at 7.40 x 7.30 m.