The oldest part of the Sjonhem church is the tower, which was built in the 13th century. Originally it was attached to a much smaller Romanesque church. The choir and nave was however torn down and replaced with the current structure during the middle of the 13th century.
Inside, church frescos decorate the vaults; these also date from the 13th century. Also probably original are some stained glass windows. A crucifix on the altar is somewhat later, dating from the 14th century. The baptismal font is however considerably older, dating from the 12th century and thus older than the church itself. It was made by the stonemason known as Hegvald. The church has been largely unaltered since the Middle Ages; the greatest change occurred in 1818 when the sacristy was built.
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.