Kastellet, Stockholm

The round brick tower before you is Kastellet, a small citadel on Kastellholmen in central Stockholm. Its present form was created after an explosion in 1845, when Fredrik Blom redesigned the fortress; construction followed from 1846 to 1848. The structure combines a circular tower with red brick walls and a stair tower rising 20 metres.

Its military role returned during the Second World War, when the tower and battery received rapid-fire anti-aircraft guns. The most distinctive living detail is the Swedish naval ensign at the tower’s summit: it is raised and lowered every day, signalling that Sweden is at peace. The site began as a fortification built in 1667 under Erik Dahlbergh. Later, in 1996, Norwegian residents briefly replaced the Swedish flag with Norway’s on Constitution Day.