In the 9th century, a wooden castrum was built on a rocky promontory to fend off Viking raids near Durivum (Saint-Georges-de-Montaigu). Later, a stone keep was added with strategic upgrades, including a drawbridge. The Montaigu family, later known as Belleville, pledged loyalty to the Plantagenets. Over time, the property changed hands through marriages and alliances, including a notable period of privateering by Jeanne de Belleville. The fortifications of Château de Montaigu were enhanced in the 15th century under Louis XI's guidance to protect against Breton threats.
Some visible remnants still exist. Originally, there was an oval-shaped enclosure with about ten towers and an entrance gatehouse located in the northeast. The fortified town was situated to the north of the fortress and extended slightly to the east. A dry moat separated the fortified town from the fortress. A barbican protected the entrance gatehouse. A Romanesque keep of the Niort type, with its courtyard and a small enclosure, was located in the castle's courtyard, roughly in the middle in the north-south direction and facing west.
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.