Prøvesten is a sea fort in Copenhagen's Coast Defences. The fort was built in 1859-1863 on a man-made island off the Sound Coast of Amager. The fort's specific task was to protect the approach to the port of Copenhagen through the narrow channel of Kongedybet and to prevent bombardment of the capital from the sea. Prøvesten was decommissioned as a sea fort in 1922 and sold to Copenhagen Port Authority in 1934. Since then the fort has been used as part of the new Copenhagen Oil Terminal for storing, shipping and piping oil, bunkers and jet fuel.
Copenhagen has come under bombardment twice in its history – in 1700 and 1807. In 1700, an allied Anglo-Dutch-Swedish fleet bombarded Copenhagen from the sea. Lessons learned from this bombardment were applied in development of the coastal defence line in the 18th and 19th centuries. The first stone in the fortifications was laid in 1713. A number of decommissioned warships were run aground to form a coastal defence line in the northern and southern sections of the port of Copenhagen. This was the forerunner for the later sea forts of Trekroner and Prøvesten. In 1807, in the face of this strong new naval defence, the British army switched to bombardment of Copenhagen from the land side. Experiences gained from the British assault had great influence on the land fortifications built in the late 19th century.