The Stone Alley Tower was intended to secure two gates, the gate of the Long Alley and the gate of the Stone Alley. The name suggests that Steingasse was one of the few fortified alleys in the city. This was something so special that the alley and the tower got their names from it. Also, like the Hospitalturm, the Steingassenturm was added to the city wall only when it was already standing. The construction joints between the tower and the wall can still be seen today. It was also built as a three-sided shell tower. The side open to the city was intended to prevent an enemy from taking refuge in the tower once he had conquered the wall. Shuttering towers with one side open to the city caused static problems. The lack of stability of the fourth side of the wall was replaced by the medieval builders with a system of wall ties made of thick oak beams. The system can be clearly seen in the wall holes for the beams. Originally, a wooden walkway ran around the top of the tower. However, when this tower also tilted, the battlement was broken off and another storey with a battlement was built vertically. The tower can be climbed today. From the top, the course of the city fortifications is clearly visible.