The arms are derived from the old banner of the city, and is used on seals since 1394. The colours are known since 1443. The shield itself thus has not changed since.
Until the early 18th century the arms were often shown besides the Imperial eagle, as the area was part of the Holy Roman Empire. In the late 18th century the power of the empire became less and less and the eagle was replaced by the ducal crown. The lions were added around the same time.