The Romanesque church tower is the oldest part of the church. It was built circa 1200. Originally it was attached to a Romanesque church, the nave and choir of which however was replaced with the presently visible Gothic parts at the end of the 13th century. The sacristy is the only non-medieval part of the church; it was built in 1866. The exterior of the church is decorated with Romanesque reliefs, re-used from the earlier church and incorporated into the Gothic structure. Inside, the choir retains traces of original church frescos.
Several of the church fittings are medieval. The baptismal font dates from the 12th century and was made by the sculptor Hegvald; it is considered one of the artist's finest pieces. The church also houses a triumphal cross from the same century. The altarpiece is also medieval but was altered in the 17th century. Most of the other fittings, such as the pews and the pulpit, date from later centuries.
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.