St. Nicolai Church dates to the 13th century. Originally built in late Romanesque style and dedicated to the patron saint of merchants and seafarers, the church is the oldest building in the community. Renovations in the 15th century developed the church into a Gothic hall with two transepts and a tower 27.2 m high.
On display in a glass-covered sarcophagus in the northern transept are the remains of the Haraldskær Woman, one of the best conserved of the iron age bog bodies. The southern transept houses the sarcophagi of Kai de la Mare and his wife. The exterior brick wall of the north transept has an interesting feature of 23 spherical indentations approximately 15 cm in diameter, which hold the skulls of 23 robbers who were caught and beheaded in the nearby Nørreskov forest. In front of the church stands a sculpture of the priest Anders Sørensen Vedel.
The church was seriously damaged during the Thirty Years' War by the Catholic troops of Wallenstein. Since that time it has undergone several major restorations: in 1744, 1855-56, 1887-88 and 1964-66.
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.