Forts in Cologne, Military fortification ring in Cologne, Germany

The Forts in Cologne are the remains of two Prussian fortification rings built around the city from 1815 onward: an inner belt and an outer belt of forts and intermediate works. The outer ring grew to 177 installations after concrete shelters were added between 1905 and 1914. Most ditches were filled in from 1924, but the gorge walls of many forts remain open.

The Prussian administration began construction of these strategic fortifications in 1815, incorporating elements from earlier Roman and medieval defenses. The rings were designed to protect the city from military attacks and expanded over several decades.

Many former fortifications now function as event venues, parks, or sports facilities where residents spend leisure time. Some structures host exhibitions and guided tours where visitors learn more about construction methods and military use.

Visitors reach individual forts via the outer ring road, which links different sites together. Many installations are freely accessible, while some open only during guided tours or at specific times.

The outer ring's forts are linked by the Militärringstraße, at about 21 km the longest street in Cologne; for most of its course it runs through parkland. Some forts are now used by clubs, while others are bricked up and serve as bat roosts.