In 1557 the church assumed its present form, with the guardroom, the bay windows and the steep roof. Over the centuries, the tower fulfilled several functions. It provided a secure access to the city that was locked every night and also served as a prison and as a watchtower to detect fires at an early stage. Since 1480 it was possible to see what "Zyt" (time) it was. The large clock was installed in 1574. Of particular interest today is the astronomical clock. The four hands, with the sun, moon, arrow and S, indicate the month, the phase of the moon, the day of the week, and the leap year. Fastest of all is the week hand. Every day it passes over one of the seven deities from whom the names of the days have been derived.