The early medieval settlement complex in Kałdus was, apart from Gdańsk, the most important settlement center in Eastern Pomerania in the early Middle Ages. Its strategic and political importance was determined by its convenient location at the intersection of the two main trade routes: the Vistula and the Ruthenian-Baltic routes. In the first half of the 11th century, there was a political center of Bolesław Chrobry and Mieszko II, consisting of a hillfort with a defensive ramparts, a settlement near the hillfort and a village with a cemetery. The construction of the basilica church has also begun. The function of the great sacral complex, founded on the periphery of the early Piast state, remains a mystery. The basilica was not completed, walls were raised to a height of about 1 meter, after which the construction was abandoned, probably due to the pagan reaction after 1034. The final end of the hillfort took place in the 20s of the 13th century, when the Prussians captured it and burnt it. The Teutonic watchtower, which was established in the 40’s of the 13th century, was quickly demolished.
The hillfort rampart had a kidney shape with dimensions at the base: length from the inner 100 meters, from the outer 140 meters, the width at the base of 50 meters, and the height from the east side 15 meters.
The walls of the hillfort temple, preserved in places up to one meter high, were built of stone. The exceptionally large dimensions of the building, approximately 36-37 meters long and 15 meters wide, can be compared only with the size of the cathedral churches existing at that time in Gniezno and Poznań. It had three naves, three apses, including two side ones and one main one orientated towards the east, and a small annex ended with a semicircular apse located on the western side.
At present, the hill is protected as a steppe vegetation reserve St. Lawrence Mountain. There are no relics of buildings preserved on it, but the hillfort itself is legible.
Webpage odznaka.kuj-pom.bydgoszcz.pttk.pl, Góra św. Wawrzyńca W Kałdusie.