The vassal tower-stronghold of Angerja was probably built in the 14th century. The rectangular construction was made of limestone, the walls were two meters thick and it was surrounded by a moat. Some parts of the walls remain to this day and a moat is still visible. It is thought that the stronghold was destroyed during the Livonian war.
Tower-strongholds were built by vassals to protect themselves, mostly against peasant uprisings, especially after the failed St. George's Night uprising of Estonian peasants in 1343.
Reference: 7is7.com
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.