The castle's story dates back to a fortress, Krogen (lit. English: the Hook), built in the 1420s by the Danish king, Eric of Pomerania. The king insisted on the payment of sound dues by all ships wishing to enter or leave the Baltic Sea passing through the Sound; to help enforce his demands, he built a powerful fortress at the narrowest point in the Sound. At the time, the Kingdom of Denmark extended across both sides of the Sound, and on the eastern shore the Helsingborg Castle had been in existence since the Middle Ages. With the two castles and guard ships it was possible to control all navigation through the Sound.
The castle was built on Ørekrog, a sandy tongue of land stretching into the sea from the coast of Zealand towards the coast of Scania. The castle consisted of a square curtain wall with a number of stone buildings inside. The stone building in the northeastern corner contained the king's residence. The building in the southwestern corner contained a large arched banquet hall. The building in the southeastern corner possibly served as the chapel. Large portions of the walls of Krogen are contained within the present-day Kronborg Castle.
King Christian III had the corners of the curtain wall supplemented with bastions in 1558-59.
Frederick II's Kronborg
From 1574 to 1585 Frederick II had the medieval fortress rebuilt into a magnificent Renaissance castle, unique in its appearance and size throughout Europe.
As a consequence of developments in the military technique of the era and the improved striking power of the artillery, it became clear that it was necessary to modernize the fortifications of Krogen. After the conclusion of the Northern Seven Years' War in 1570, King Frederick II initiated an extension of the advanced bastions to relieve the medieval curtain wall. The main architect was the Flemish architect Hans Hendrik van Paesschen and the fortification works were completed in 1577. After this the
