To be privately owned
Langlütjen II Fortress

Fortress Langlütjen II is an artificial island in the Weser estuary, created in the 19th century as part of a military defense system. Located in the Lower Saxon Wadden Sea, it once served to protect the ports of Bremen and Bremerhaven. This facility is privately owned.
History+
The island of Langlütjen II was artificially raised between 1872 and 1876 to house a fort, which became operational in 1880. This fort was designed for a garrison of 100 men and was equipped with heavy cannons during World War I, though it saw no combat. After the war, the military installations were dismantled. Langlütjen II experienced a period from September 1933 to January 1934, when it served as a provisional SA detention camp. After World War II, the island was sold by the federal government and is now privately owned.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: https://de.wikipedia.org/wiki/Datei:Langl%C3%BCtjen_II_%28Insel%29_2013-05-03-DSCF7456.jpg
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 53.5739, 8.4953