The construction of defensive walls in Gniew started just after the location of the city in 1297. Work on them continued in the fourteenth and fifteenth centuries. In the 17th century, due to the growing threat from the Swedes, medieval fortifications were strengthened by ramparts and earth bastions. Beginning with the 18th century, the city fortifications of Gniew began to fall into ruin, in the 19th century demolition of all city gates and parts of the gothic defensive walls was carried out.
The length of the fortifications was about 750 meters. The walls were reinforced with 16 towers with a rectangular plan, two-story, open from the side of the city and protruding from the front of the walls. Two of them were round. Four gates led to the city: the Malbork Gate, the Gdańsk Gate, the Water Gate and the Castle Gate. In the vicinity of the Malbork Gate, the wall was connected with the fortifications of the castle. The old Mill Gate from the south and the newer Dybów Gate in the north, enabled communication between the city and the castle, access to the mill and fishing. The walls were made of brick, but they were placed on a special foundation about 1 meter high, in which irregular stone boulders were combined with brick rubble. In the wall two types of bonds were used, flemish and monk.
The largest remains of defensive walls have survived along Górny and Dolny Podmur streets, while the tower on Sobieskiego street.