The Church of San Dionisio was built in the late 15th century in Gothic-Mudéjar style, although its interior was later renovated in Baroque style (18th century) by architects Diego Antonio Díaz and Pedro de Silva.
The parish was established by Alfonso X the Wise in the name of Saint Denis as the city was returned to Christian rule on Saint Denis's Day in 1264.
The church has a basilica plan, divided into three naves by tall and simple pillars adorned with Almohad decorations. The arcades (aside from those near the high altar) are ogival. The naves end with apses with Baroque altars, including the high altar which dates to the pre-Baroque renovation.
The side chapels are in Baroque style. The chapel of the Christ of the Water includes an image of Jesus from the 15th century. The tower known as Torre de la Atalaya was also built in the fifteenth century. Although this is attached to the church it was a civilian construction intended to serve as a watchtower for both fires and attack and to hold the town's clock. The tower has been separately listed from the church as being of cultural interest. The tower was first mentioned in 1447 and the clock was installed in 1454 and the tower was first used as a watchtower in 1484.
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.