Saint Nicholas Church is a small Gothic church where Jean Calvin led services and preached in 1538. The Church no longer functions as a parish church, today it is used by a Charismatic group called 'Renouveau Saint Nicholas'.
The church was built between 1387 and 1454 on the site of an earlier church dedicated to Mary Magdalene. This earlier church, which dated from 1182, was founded by the Knight Walther Spender and had been built on the site of a small Roman fort. The tower with its tapering spire was erected in 1585 . The interior was remodeled during the 17th Century. The façade and the sacristy, which date from 1905, are by Émile Salomon, the architect of the Temple Neuf.
The interior contains remains of 15th Century frescoes. The 1707 organ of the brothers Andreas and Gottfried Silbermann was dismantled in 1967.
References:The Clementinum is a historic complex of buildings in Prague. Until recently the complex hosted the National, University and Technical libraries, the City Library also being located nearby on Mariánské Náměstí. The Technical library and the Municipal library have moved to the Prague National Technical Library at Technická 6 since 2009. It is currently in use as the National Library of the Czech Republic.
Its history dates from the existence of a chapel dedicated to Saint Clement in the 11th century. A Dominican monastery was founded in the medieval period, which was transformed in 1556 to a Jesuit college. In 1622 the Jesuits transferred the library of Charles University to the Klementinum, and the college was merged with the University in 1654. The Jesuits remained until 1773, when the Klementinum was established as an observatory, library, and university by the Empress Maria Theresa of Austria.