Gradačac is a city and the center of the same-name municipality in the northeastern part of Bosnia and Herzegovina. It is situated on the slopes of Majevica and Trebava mountains, at the altitude of 129 meters. Symbol of the town is the Husein-Captain Gradaščević Tower, fort of extraordinary beauty built in the Bosnian architectural style. The construction of the tower was completed in 1821.

The architectural ensemble of the Old town in Gradačac is designated as a National Monument of Bosnia and Herzegovina. The National Monument consists of the ramparts and the buildings within them: the Upper Fort with the Husein-Captain Gradaščević Tower, and the Lower Fort with the Clock Tower, the town Library, the radio station, the Museum, and the Grammar School.

Husein-kapetan Gradaščević was a Bosniak general who fought against the Ottoman Empire and new reforms implemented by the Sultan Mahmud II which abolished the ayan (landlord) system. He is often referred to as "Zmaj od Bosne", meaning "the Dragon of Bosnia".

When Husein took over the Gradačac captaincy, he focused most of his attention on administration of internal affairs. It is notable that all of Husein's construction projects were related to the city of Gradačac and its immediate area. During his rule, Gradačac further expanded its status as one of the most prosperous captaincies in Bosnia.

The first and most notable construction was that of the Gradaščević family castle.

Within the Gradačac city walls Husein's most significant contribution to the city was the clock tower (Bosnian: sahat-kula) which was built in 1824. The object's base is 5.5 by 5.5 meters, while the height is 21.50 meters. It was the last object of this type to be built in Bosnia.