The alms tower (22.50 m high, area approx. 5.40 x 5.40 m) stands on the south-east corner of the city fortifications and borders on the Mühlbach, which has since been abandoned. It is the most beautiful tower by the master builder Wolze Spede and is considered the symbol of the city.
The alms tower actually consists of two towers placed one on top of the other. The lower tower has rougher corner ashlars in the lower part than in its later elevation. It has three floors, is 16.40 m high and ends with a crenellated wreath on a round arch frieze. At its corners there are gargoyles designed as animal mouths.
The 8.10 m high, smaller upper tower (basic area 3.60 x 3.60 m) sitting on the lower tower was built later (probably around 1550) and also ends with a crenellated crown of battlements. This construction method resulted in a recess in the tower, which was used as a surrounding battlement, while the tower above it served as a raised lookout.
The main reason for erecting such mostly round towers, known as churn towers, was therefore probably less of a strategic and more of a symbolic nature. In Obernburg, a square shape was chosen on the side of the city facing the Main.