A walk through history shows us that the area of the municipality was populated even in prehistoric times, evident in the finds in the vicinity of the Kaplje village. Ilyrians and Celts lived here, confirmed by Hallstatt findings in Boštanj. At the beginning of the calendar era these places became the property of the Roman Empire. 

The archeological sites in Ajdovski gradec above Vranje from the 5th and 6th century AD, where they found traces of late Roman and early Christian settlements, show the turbulent times of migration. In the late Middle Ages, Sevnica was first mentioned in 1256, when the area belonged to the Salzburg Archbishops and after the brief rule of the Hungarian kings it came under Hapsburg rule, which was maintained until the end of the First World War. 

Turkish invasions and peasant revolts also affected the Sevnica area. In the 1573 peasant revolt the area was even occupied by the rebellious peasants. That is why the upper Sevnica Castle was fortified in the 16th century.

Sevnica was not spared by either fires or the plague. The market burned repeatedly, most recently in 1854 and the plague massacres are evidenced in numerous plague columns and the fortified church of Saint Rok above Sevnica. Sevnica was granted market rights in 1322, however, the right to organize fairs was granted only in 1513 by the Salzburg archbishop and in 1783 Emperor Joseph II. allowed annual cattle fairs. The architecture of the medieval Sevnica Castle was first spoken of in 1309, but the crew mentioned in 1292, surely tied to the upper castle, is a silent witness of many time periods – from the Renaissance to the Baroque. Near the castle there is a 16th century Lutheran cellar, one of the most beautiful Renaissance artistic monuments in our country, which boasts not only beautiful paintings, but also outstanding acoustics. As the name suggests, the cellar was a Protestant shelter. It is rumored that Jurij Dalmatin taught Lurther’s doctrine there.  

The lower Sevnica Castle, made in 1613, is the oldest building in the Main Square; the central, oldest part of Sevnica along with the Neo Roman parish church of Saint Nikolaj, the cruch of Saint Florjan from 1443 and the restored monument with the statue of Saint Martin from the 17th century. Today the seat of the Sevnica municipality lies in the lower castle and the square still retains its original state. 

Sevnica was also affected by the 19th century Slovenian national movement. In 1866 the first reading room in Posavje region was founded here joined by a camp in 1869, where many nationally conscious Slovenes requested a united Slovenia. This strong camp movement greatly marked the area’s history. 

On the rounded hills large and small churches stand as solitary guards. Many of them are protected monuments and still emphasize the original beauty and integrity of the natural environment.