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 Petersberg Citadel is one of the largest extant early-modern citadels in Europe and covers the whole north-western part of the Erfurt city centre. It was built after 1665 on Petersberg hill and was in military use until 1963. It dates from a time when Erfurt was ruled by the Electors of Mainz and is a unique example of the European style of fortress construction. Beneath the citadel is an underground maze of passageways that can be visited on guided tours organised by Erfurt Tourist Office.
The citadel was originally built on the site of a medieval Benedictine Monastery and the earliest parts of the complex date from the 12th century. Erfurt has also been ruled by Sweden, Prussia, Napoleon, the German Empire, the Nazis, and post-World War II Soviet occupying forces, and it was part of the German Democratic Republic (East Germany). All of these regimes used Petersberg Citadel and had an influence on its development. The baroque fortress was in military use until 1963. Since German reunification in 1990, the citadel has undergone significant restoration and it is now open to the public as a historic site.