The church of the Assumption was founded in the years 1326-1364 by princess Zofia, wife of Barnim IV. Initially Knights Hospitaller patronized it. In the first half of the fifteenth century it was enlarged by a northern chapel and a rows of chapels by the tower. Temple equipping continued until the second half of the 15th century. Since the 16th century the church was a Protestant temple and returned to Catholics after the Second World War. At the end of the 19th century, the building was restored in the neo-Gothic form, unfortunately many architectural details were replaced at that time (windows tracery and windows reveal). After the Soviet troops entered Sławno in 1945, the church was destroyed. The interior of the nave and tower was then burned down, and the vault over the presbytery collapsed. The Franciscan Order, which took care of the temple, began its rebuilding, which lasted until the end of the 1950s.
The church was erected east of the town square market. It was built of bricks laid in the monk bond on stone foundations. It is a three-aisle basilica founded on a rectangular plan with a lower, polygonal chancel on the east side and a four-sided tower on the western side. In the fifteenth century, a four-bay chapel was built on the north side on the unusual plan of the letter “L” and a small two-bay sacristy from the south. The high church tower is four-storey and covered with a tent roof. The central nave adjacent to it was covered with a gable roof, separated by a gable from a slightly lower roof covering the chancel.
Outside, the church is surrounded by buttresses, between which there are pointed arch windows. As the walls of the central nave are only slightly higher than the chancel walls and do not extend above the roofs of the side aisles, the windows of the nave are visible from the outside only as small pointed arches. The lateral aisles create, along with the adjoining chapels, solid blocks, only diagonally set buttresses signal the secondary extension of the side aisels by three bays to the west. The side gables of the aisles are filled with blendes, while under the eaves of the chancel and the central nave, a moulded bricks have been guided. The decoration of the gables of the northern chapel with ogival blendes between lesenes passing into the pinnacles is also distinguished from the relatively raw church facade. The rather modest west façade of the tower with a moulded portal in the ground floor has a large window and above it a series of triangular blendes and low pointed blendes. The side elevations of the tower in addition to triangular blendes have a series of narrow and high ogival niches.
In the interior of the church, three pairs of octagonal pillars carries ogival arches, separating four rectangular bays in the main nave and square bays in the aisles. The chancel consists of two rectangular bays, closed with a polygon. The ground floor of the tower was constructed on four massive pillars forming a monumental porch, open both from the side of the central nave and side aisles. In the presbytery, large three-light windows were placed in niches formed by pilaster strips on which ribs of the stellar vaults flow. On the wall of the chancel arch from the side of the central nave there are also traces of the planned, but not realized, lower than the current vault. The walls of the main nave were divided over the arcades by a wide belt separating the window storey, in which the window niches descending to this level were bricked up, except for the pointed ogival tops. On the axis of the pillars rise moulded lesenes, into which the ribs of the stellar vaults flow in the upper parts. Six-armed stars with a guide rib were used here, which eliminates divisions between bays, as well as eight-armed stellar vaults in side aisles and the northern chapel.
Architektura gotycka w Polsce, red. T. Mroczko i M. Arszyński, Warszawa 1995.
Jarzewicz J., Architektura średniowieczna Pomorza Zachodniego, Poznań 2019.
Pilch J., Kowalski S., Leksykon zabytków Pomorza Zachodniego i ziemi lubuskiej, Warszawa 2012
Website: mariackaslawno.pl, Historia kościoła.