St. Nicholas Church is a Baroque church in the Lesser Town of Prague. Built in the thirteenth century AD, this church was designed by Giovanni Domenico Orsi and is also dedicated to Saint Nicholas. This church is distinguished by its complex geometric system, the central dome, the wide nave, and the side chapels. The 65-meter-high church tower was completed in 1752 AD, and it was designed by Dientzenhofer, and was used as an observatory for state security during the communist era.