In the second half of the 13th century, construction of defensive walls began around the Cistercian monastery in Kołbacz. The work was completed in 1349. The wall was probably not high. It was a brick wall 2.5 meters high and about 0.5 meters thick. Its total length was about 1000 meters. The wall had three entrance gates and was reinforced with several towers. Only one of these towers, called the Prison Tower, has survived to this day.
The only remnant of the Kołbacz fortifications that has survived to this day is the prison tower. The prison tower was built in 1349, near the bridge over the Płonia River, opposite the Abbot's house. Built in the 13th century, the monastery was surrounded by walls and towers to defend it against invaders. And they attacked extremely often. In 1242, when the Duke of Szczecin learned that the monks had accepted German protection, he invaded and completely plundered the Cistercian estate. In 1273 and 1478, the monastery complex was attacked by the Brandenburg army, and in 1433 the Hussites became the invaders. Due to frequent attacks, the monks decided to build defensive walls and a moat. Of the fortifications, only the prison tower has survived, which once housed a prison dungeon. The facility was built of red brick, its gable is topped with a gable roof. There are small, rectangular window openings in the walls of the tower. Inside we will find an empty space where the door used to be, but with the hinges preserved in the wall. The tower is unique on a nationwide scale, it is the only remnant in the country of the fortifications that served to defend the monks' property. Adjacent to the tower is a residential building that is several hundred years old and houses the industrial and food store "Pod Basztą." Of the entire complex of medieval monastery buildings, the prison tower is one of the few buildings that has survived in very good condition. Despite this, the facility has not been renovated for years. The prison tower with a Gothic barn and the lay brothers' refectory were included on the list of monuments in April 1955. The facility is renovated.