Kastellet is one of the best preserved star fortresses in Northern Europe. It is constructed in the form of a pentagram with bastions at its corners. Kastellet was continuous with the ring of bastioned ramparts which used to encircle Copenhagen but of which only the ramparts of Christianshavn remain today.
King Christian IV of Denmark initiated Kastellet’s construction in 1626 with the building of an advanced post, the Sankt Annæ Skanse (St. Anne's Redoubt), on the coast north of the city. The redoubt guarded the entrance to the port, together with a blockhouse that was constructed north of Christianshavn, which had just been founded on the other side of the strait between Zealand and Amager. At that time the fortifications only reached as far north as present day Nørreport station, and then returned south east to meet the coast at Bremerholm, the Royal Shipyard. However, part of the king's plan was to expand the area of the fortified city by abandoning the old East Rampart and instead extend the rampart straight north to connect it to Sankt Annæ Skanse. This plan was not completed until the mid-1640s, shortly after King Frederick III succeeded King Christian IV.
After the Swedish siege on Copenhagen (1658–1660) the Dutch engineer Henrik Rüse was called in to help rebuild and extend the construction. The fortification was named Citadellet Frederikshavn ('The Frederikshavn Citadel'), but it is better known as Kastellet ('the citadel').
Kastellet was part of the defense of Copenhagen against England in the Battle of Copenhagen (1807). During the German invasion of Denmark on 9 April 1940, German troops landing at the nearby harbor captured The Citadel with very little resistance, thereby forcing the Danish government to surrender.
Kastellet was renovated 1989–1999 with funds from the A.P. Møller and Wife Chastine McKinney Møllers General Fund.
A number of buildings are located within the grounds of Kastellet, including a church as well as a windmill. The area houses various military activities but its mainly serves as a public park and a historic site.
References:Ogrodzieniec Castle is a ruined medieval castle originally built in the 14th–15th century by the W³odkowie Sulimczycy family. Established in the early 12th century, during the reign of Boles³aw III Wrymouth, the first stronghold was razed by the Tatars in 1241. In the mid-14th century a new gothic castle was built here to accommodate the Sulimczycy family. Surrounded by three high rocks, the castle was well integrated into the area. The defensive walls were built to close the circuit formed by the rocks, and a narrow opening between two of the rocks served as an entrance.
In 1470 the castle and lands were bought by the wealthy Cracovian townsmen, Ibram and Piotr Salomon. Then, Ogrodzieniec became the property of Jan Feliks Rzeszowski, the rector of Przemy¶l and the canon of Cracow. The owners of the castle about that time were also Jan and Andrzej Rzeszowskis, and later Pilecki and Che³miñski families. In 1523 the castle was bought by Jan Boner.