Sielecki Castle is located on the left bank of the Czarna Przemsza River. Originally a defensive fortification, the castle expanded in 1620 into a four-wing complex with corner towers, perhaps using earlier buildings. The castle was built of broken limestone and brick. Storey building with basement. After the fire in 1824, the castle was rebuilt in 1832, but the east wing with the entrance gate was demolished and the moats were filled. Despite these changes, the original defensive character is evidenced by the shape of the block, four corner towers and projections on the extension of the side wings. It is currently a three-winged building with an open courtyard.
In 1994 the city of Sosnowiec took over the destroyed castle. Currently, the castle houses the Sosnowiec Art Center. This local government institution co-creates the cultural life of the city by organizing exhibitions, concerts and various culture-forming meetings.
References:From its origin as a small stronghold built by the ancient Illyrian tribe Dalmatae, becoming a royal castle that was the seat of many Croatian kings, to its final development as a large fortress during the Ottoman wars in Europe, Klis Fortress has guarded the frontier, being lost and re-conquered several times. Due to its location on a pass that separates the mountains Mosor and Kozjak, the fortress served as a major source of defense in Dalmatia, especially against the Ottoman advance, and has been a key crossroad between the Mediterranean belt and the Balkan rear.
Since Duke Mislav of the Duchy of Croatia made Klis Fortress the seat of his throne in the middle of the 9th century, the fortress served as the seat of many Croatia"s rulers. The reign of his successor, Duke Trpimir I, the founder of the Croatian royal House of Trpimirović, is significant for spreading Christianity in the Duchy of Croatia.