Although this baroque belfry, which was also used as a fire tower and the night watchman residence, was built together with St. Nicholas’ Church, its greater part was built after the church was finished. The outstanding Baroque architect, Kilian Ignaz Dientzenhofer, designed and built the belfry tower. His apprentice and son-in-law, Carlo Lurago, added some details. The construction was finished as early as 1752, although the official recordings state 1755. Two years later, the building was damaged during the Prussian siege of Prague.
The tower is as tall as the dome of the adjacent church. The gallery is 65 m high and may be accessed by 215 steps.
At first glance it may seem that the tower belongs to the Church of St. Nicholas; however, it never belonged to the church because it has always been the municipal property of the Lesser Town. In the 1960s, the purpose of the building became the observation post of the state police, which monitored the western countries embassies residing nearby.