In the context of castle-town settlements history in Pomerania, which was introduced earlier, the character and the origin of Slupsk castle-town is clearer. This castle-town was a small centre of defence from the beginning of 9th century. Due to its early date of origin it should be considered as one of the tribal centres of the Grabowa, Wieprza, Slupia and the Lupawa river-basins. Due to its not large sizes, however, it is considered that it gained the significance within a period of early feudal order of Slawno statehood.

This castle-town was found on the right riverside of the Slupia. It was placed on the island formed by branches of the Slupia river (today they do not exist), spreading eastward from her today's river-bed. It was a place of trade and strategic meaning - river crossing, on the important communication route which connects Gdansk with Szczecin and Wolin. Today, the church of St.Otto is situated in the place of the former river crossing.

The surface of the old castle-town remained in the form of the cone-shaped elevation of about 50-metre diameter. Today this elevation is limited with certain streets: Partyzantow Street - from the western side, Henryk Pobozny Street - from the eastern side and with Koscielna Street from the southern side. The castle-town itself was surrounded with an embankment with wooden bales, which was strengthened by the stone structure at the bottom. During the earthworks led on this location in different times, some quantities of the different kind of ancient monuments were discovered. During archaeological works led in 1966-67 a lot of ceramic and metallic exhibit goods, such as iron-nails, the vinculum and nits, the hook for fishing, the grots of arrows, iron-knives, the chisel, clay-spindle whorls as well as the fragment of the whetstone were found.

The detailed analysis of all archaeological findings showed that the Slupsk castle-town should be dated on 9th÷12th century. To the north of the existing castle-town, on the right riverside of Slupia, the early-mediaeval 'open' settlement existed. The colony was found within today's streets: Kaszubska, Kosciuszko and Traugutt Street. At the Traugutt Street ceramic antiquity was found. They were partially formed by hands or coated on the potter's wheel. A lot of burning traces (wood coal) and a lot of animal bones were also found there.

On the right riverside of the Slupia there is also one more, very important place in early-mediaeval history of Slupsk. At present the place is situated next to the square of the Church of Najswietsze Serce Jezusowe. The oldest, non-existing Church of St. Piotr in Slupsk was situated there in a place of today’s Najswietsze Serce Jezusowe Church. During the construction of actually existing church in 19th century, the stony plate with the representation of the pagan deity was discovered.

This plate has a form of the granite block of 125 cm of the height, 66 cm of the width and 18 cm of the thickness. This is the stony bas-relief with the representation of the human personage. The plate is one of the most precious Pomeranian findings, objects connected with the religious cult. This is also the indirect proof of the purposeful location of the first church in Slupsk in a place of the former pagan cult.