Loučeň Castle was built on the site of a former medieval fortress. The first mention of this fortress dates back to 1223 and was discovered in the testimonial of the Prague bishop Peregrinus. This year is also considered the first official mention of the village of Loučeň. From that time until 1618, several lords and peasants alternated as owners of the fortress.
In 1612, the castle of Loučeň and other adjacent villages were owned by Václav Berka of Dubá the Elder, a very wealthy nobleman who did not sympathize with Emperor Ferdinand II. Therefore, in 1620, after the Battle of White Mountain, Václav Berka left the country and the castle was confiscated in 1622 due to his participation in the anti-Habsburg uprising. A year later, all of Berka's property was purchased by Adam of Valdštejn.
During the Thirty Years' War, all the surrounding villages in the Nymburk region were heavily affected by the invasion of armies. The dilapidated fortress in Loučeň was not renovated until 1704-1713, when Karel Arnošt of Valdštejn began to transform it into a Baroque castle. A chapel was also added to the castle, which was later converted into the Church of the Assumption of the Virgin Mary. After Karel Arnošt's death, his daughter Eleanora took over the estate, and she passed it on to her daughter Maria Anna. She was very determined, persecuted evangelicals, and tightened the requirements of serfdom. Maria Anna married Josef Fürstenberg, and thus the ownership of Loučeň Castle passed from the Valdštejn family to the Fürstenbergs.
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.