It is unknown when the construction of Krzyżtopór impressive fortress began. The first documented proof of the construction of the castle comes from 1627, when it was uncompleted. It was probably finished it in 1644, having spent the enormous sum of 30 million Polish zlotys on the work. The castle was inherited by Ossoliński's son Krzysztof Baldwin Ossoliński, who died in 1649 in the Battle of Zborów. After his death, the formidable complex was purchased by the family of the Denhoffs, then by the Kalinowskis.
In 1655, during the Swedish invasion of Poland, the castle was captured by the Swedes, who occupied it until 1657, pillaging the entire complex. The damage to the structure was so extensive that after the Swedes’ withdrawal it was not rebuilt, as it was deemed too costly. Several noble families (the Morsztyns, the Wiśniowieckis and the Pacs) lived in the best preserved, western wing, but the castle otherwise remained in ruins.
In 1770, during the Bar Confederation, Krzyżtopór, defended by the Confederate units, was seized by the Russians, who completed the building's ruin. Reportedly, last known inhabitant of the complex, Stanisław Sołtyk, lived there in the years 1782–87, after which time Krzyżtopór has been abandoned.
During the Second World War the complex was again ransacked. A partial remodeling took place in 1971, and in 1980 the Polish Ministry of Internal Affairs decided to rebuild it for use as a rest area for officers. This work was halted in 1981, when martial law was imposed in Poland.
Today the castle, without convenient proximity to main roads and rail connections, is visited by relatively few tourists. However, as walls, bastions and moat are relatively well-preserved, its magnitude is still very impressive. Though it is regarded as a permanent ruin, since around 90 percent of the walls have been preserved, reconstruction has been planned several times. Currently, efforts have been underway to roof the entire complex; however, this ambitious project lacks sufficient funding.
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.