'Kastellet' photo (c) 2007, elchicogris - license: http://creativecommons.org/licenses/by-sa/2.0/
The official name is the Citadel of Frederikshavn but for centuries it has been Kastellet in every day's speech. This Copenhagen fortification was planned and commenced by Christian lV and expanded by Frederik lll after whom it's named.

Inside the Citadel the king even planned to build a royal palace. A dream which never came through, but a church was built within the Citadel as well as a prison, a windmill, Commandant's quarters and other houses.

Kastellet was in use during the Battle of Copenhagen in 1807. The worst blow in modern time to this historic site came when Germany invaded Copenhagen in 1940. The German troops landed right here at Kastellet and blew up one of the 17th century portals.

Today Kastellet is open to the public and many choose it for a stroll.