The ancient Pieniny castle was built on northern slope of a steep hill. The complex was small, due to lack of space, but placed in a spot which provided natural defence. The length of the defensive walls was 88 meters, and the walls were 1 meter thick, made from the local limestone rock. The gate was located in western part of the castle, below which cellars were built. According to Jan Długosz, during the disastrous Mongol invasion of Poland (1259), Prince Boleslaw V the Chaste fled to the Pieniny Castle (spelled as Castro Pyeniny), together with his mother and wife Kinga of Poland. Historians however doubt Długosz, claiming that construction of the castle was not initiated until the 1280s. The complex guarded southern border of Lesser Poland, and probably was abandoned by the first half of the 14th century, to be destroyed in the 15th century (most likely in 1433, during a Hussite raid.
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.