The first timber town fortifications were destroyed in 1242/1243 during the first Prussian uprising against the Teutonic Order. Probably the town was deserted for a long time, because new settlers appeared there only in 1255. During the second Prussian uprising of 1260-1273, the town, which was already the property of the Pomezean bishops, was again burned and ravaged twice. After this event, at the end of the 13th century, a decision was made to build stone and brick defensive walls. Around 1336, the basic work was completed.
In the fourteenth century, the defensive wall surrounded the town of about 10 hectares, in the shape of an irregular pentagon. The fortifications were reinforced by eleven towers and three town gates. The most impressive was the north-east Malbork Gate, flanked by two towers. It contained the town guardhause and the dungeon serving as a prison. The access to the gate led through the drawbridge over the irrigated moat. Another gate in the south-east part of the town was the Grudziądz Gate, also known as High, Upper or Chełmno Gate. It was dismantled already in 1571 in relation with the development of Grudziądz suburb. The third of the town gates called Lowland or Water or Gniew Gate went out of the town to the Kwidzyn Lowland, through the oldest suburb, mentioned in documents from as early as 1336 as Podolice.
The short fragment of the town defensive wall, south-west of the castle, has been preserved to the present day. None of the town towers or gates have survived.
Website jerzykosacz.pl, Spacer wzdłuż kwidzyńskich murów miejskich.