The Church at the Citadel was built in 1704 in heavy Baroque style during the reign of King Frederik IV.

The prison complex on the rear side of the church
A prison complex was built on the rear side of the church in 1725. Eye holes in the wall between the church and the prison cells made it possible for the prisoners to follow the church services.

Struensee awaited his execution in Kastellet’s prison. The English explorer and pirate John Norcross was the person to be imprisoned at Kastellet for the most extensive period. He spent 32 years in the prison at Kastellet, 16 of the years in a wooden cage.