St David's Church was founded in 1187, built on the site where a famous synod was held in the sixth century. According to local legend, it is said that during this synod, which St David addressed, the flat ground rose into a mound beneath his feet, allowing him to be better seen and heard by the vast crowd that had gathered to hear him speak. The church supposedly stands on that same mound. It's possible that, in reality, it was built on the site of a Bronze Age barrow.
The central tower dates from the 12th century, which, in medieval times, had five bells in its belfry. Today there is only one bell, which was given to the church by John Inglis Jones of Derry Ormond in 1874. The 12th century nave and chancel were taken down in 1832, being beyond repair, and replaced in 1833–34. The new building was of poor quality, however, and the nave as it stands today was rebuilt in 1874, and the Chancel in 1886.
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.