Old Kostajnica architecture
According to traces and documents from the past the territory of Kostajnica was always settled. This can be testified by the remains ofprehistoric settlements, plumbing from the Roman period and several regions from the middle ages. The remains of prehistoric settlements were found in the following regions: Gradina Marinković- Tavija, Oštra glavica- Mrakodol, and Gradina- Grdanovac. The found remains from the roman period were roman water supply (Bubnjarica) and the remains of dross, i.e. iron foundry in the region of Mrakodol. Several regions from the middle ages verify the existence of life after the Romans (Crkvina-Kalenderi, the remains of the fort „Soko”, fort „Slatina”, fort „Drenovac”-Petrinja). The traces of architecture from the Austro-Hungarian period remained visible in the Municipal building and in the Magistrate building.
Municipal building
The municipal building was built in 1887 during the Austro-Hungarian rule. The first owner of the building was the Municipality of Kostajnica. The building was built with elements of pseudo-Moorish style. It is a style that Austro-Hungarian architects took over from Spain, and the basic characteristics of that style are: horseshoe arches, two-tone striped facades, usually with alternating orange/red and yellow horizontal stripes, window decorations, corner balcony, and plant decoration. and geometric elements. The angular position of the building is emphasized by the incision of the corner of the building and the balcony with a richly decorated fence, divided into two fields in which the central motif is a six-pointed star in a circular field. The authentic part of the interior, which has been preserved to this day, is the polychrome painted ceiling of the town hall divided into geometric fields decorated with floral motifs. The building suffered damage during shelling in the last war when the roof was damaged. It was renovated in 2009 when the interior was partially changed. A counter hall was formed on the ground floor, and the stone staircase and tiles in the hallway were covered with new tiles, while the exterior of the building was refreshed with a two-tone, red-yellow facade and mostly preserved in its authentic form. Then the old wooden joinery was replaced with a new one. The latest damage to the building was suffered in the earthquake that hit Kostajnica on December 29, 2020. The building is protected as cultural heritage by the Decision of the Municipal Assembly of Kostajnica.
Magistrate's Building
The Magistrate's building, better known as the "Dom", was built according to some sources in 1885, and was registered in 1887 during the Austro-Hungarian rule. The Bosnian-Herzegovinian land tax (state property) was registered as the first owner. In the courtyard behind the building there is a ground floor building that served as a gendarmerie station and a prison at the time when the Court building housed the Court. After the Second World War, the building served as an orphanage where children from war orphans were housed. For a time, the building housed an elementary school. The building also housed the republic authorities: the Tax Administration and the Employment Bureau, until December 29, 2020, ie the earthquake in which the building suffered damage. The building is protected as cultural heritage by the Decision of the Municipal Assembly of Kostajnica.