BlåtårnBlåtårn

Blåtårn was a tower in Copenhagen Castle, the Danish royal family's palace in Copenhagen, Denmark. The tower was used as a dungeon and has been known as such in history. It is not known when the tower was built, but it is known to have existed during the reign of King John I of Denmark. It existed from at least the late 15th century until destroyed in 1731–32.