You can see remnants of the old city wall with individual towers in the historic center of Duisburg. It is considered one of the oldest in the Rhineland, and dates back to the XII century. The construction of the city fortifications took place in two stages - in the XII and XIII centuries. The oldest sections of the wall, built of tufa, are located on the territory where the inner harbor is now. Later elements were already built of brick. There are 21 towers on the plan of 1566, drawn by Johannes Corputiusom, but only a few of them survived till now.
Koblenz Tower is one of the remaining towers of the city wall. It was built to commemorate the union of Duisburg with its friendly city Koblenz. It is located in the northeast corner of the best preserved section of the wall. Unlike the more common round towers, the base of Koblenz Tower, built of bricks, has the shape of a polygon. Due to its size, it was used as a watchtower.
In 1445 the city wall played an important role in the successful defense of Duisburg from the attack of the troops of the Archbishop of Cologne. But overall, Duisburg walls rarely had to prove their strength in what contributed to their relative longevity. The first building outside the walls was built only in 1820. In the 60-ies of the XX century, most of the walls and towers survived up to that time were demolished. The extant piece is only 26% from the previous length of the wall.