Fort 5 - King Frederick Wilhelm III, 19th century military fort in Kaliningrad, Russia

Fort 5 — King Frederick Wilhelm III is a hexagonal brick-and-concrete fort built in the late 19th century, 215 m long and 105 m wide, with walls up to 5 m thick. It is surrounded by a water moat 20–25 m wide and 5 m deep, a stone wall and an earthen rampart. Trees planted for camouflage grow along the rampart, and a low brick wall with small rectangular openings runs at the water's edge.

The fort was built in the 1870s-80s as part of Prussia's defensive network. During World War II, it became a battleground and demonstrated the strength of its construction when it finally fell.

The fort is named after King Frederick William III of Prussia (1770–1848), who ruled from 1797 to 1840 and led the state during the wars against Napoleon. Since 1979 it has housed a museum of the Great Patriotic War, and since 2010 visitors have been able to walk under its arches, inspect the courtyards and shelters, and see an exhibition of rare military photographs titled "The Storming of Königsberg".

The fort is accessible by public transport and sits within a park that you can explore on foot. The grounds are mostly flat and easy to walk, so you can view the outer walls and moats from different angles.

The fort's left wing was used after the war as a demolition site where sappers blew up ammunition collected from the surrounding area, so that section was destroyed by postwar clearing rather than by the 1945 assault alone.