Built outside the walls to the north of the walled enclosure, San Martín Church has a Roman origin, as confirmed by the latest archaeological explorations. After the Roman building had been apparently ruined, it was rebuilt and radically transformed in the 16th century and at the beginning of the 18th century.
In the 14th century, the tower was built on a base made of granite ashlar work and an upper body made of brick. It also stands as a belfry of Gothic tradition and shows evidence of the Mudejar Masters. The pointed openings are of particular interest and are made of decreasing horseshoe archivolts set in a panel.
In the 16th century, the layout was completed and structured into three naves separated by semi-circular arches. In the 18th century, the Main Chapel was refurbished and the side chapel and semi-spherical cupola above the Presbytery were built. Two Roman altar stones were reused in the south wall.
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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.