Kazimierz Dolny Castle can be related with the customs chamber that has existed since the 13th century. The tower, commonly known as the Łokietek Tower, was built at the turn of the 13th and 14th centuries, possibly because of the foundation of this ruler. The castle was erected a little later, because in the reign of king Casimir the Great, around the beginning of the second half of the 14th century, most probably in the 1350s. The stimulus for its construction, just like the fortifications in Lublin, could have been the Tatar invasion of 1341 and Lithuanians from 1349-1350, which devastated the surrounding lands.
In the fifteenth century, tenants was a family of Grots from Ostrów, and the longest, from 1509 to 1644, the starosty of Kazimierz was held by the Firlej family. At that time, thanks to Mikołaj Firlej, the renaissance reconstruction of the castle took place. Its slow demise began after the destruction made by the Swedes in 1655-1657 and 1707-1714. From 1774, the stronghold was already abandoned.
The castle is currently secured as a ruin with a readable layout. However, the XIII / XIV century tower has been fully preserved, being one of the most valuable monuments of this type in Poland. Both recently renovated buildings are adapted for sightseeing. Dates and opening times can be checked on the official website of the castle.
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.