Lembecksburg was a medieval ring wall with a diameter of 95 meters and a height of ten meters. According to old lore, it was constructed in the 9th century as a stronghold against the Vikings and is named after the knight Klaus Lembeck who had allegedly been residing there as a steward of king Valdemar IV of Denmark in the 14th century. After breaking his feudal oath, though, Lembeck is said to have been besieged by the king's host. Ít is disputed though whether Lembeck ever set foot on the island. Archaeological findings on Sylt island in the late 1970s suggest, however, that the Lembecksburg and similar facilities on Sylt date back to the days of the Roman Empire.
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.