Around 1200 there was a city castle in the form of a residential tower on the corner of the city fortifications that served as the seat of the imperial city bailiff. The residential tower had a circumference of 10 to 10 meters and was supplemented by a later annex with a floor area of 11 to 7 meters. Yet as early as the 16th century the building was no longer in use and gradually fell into ruins until it was completely forgotten.