Malakoff Caponier, Military fortification in Mainz, Germany.

The Malakoff Caponier is a 19th-century stone fortification on the Rhine side of Mainz, built into the city's defensive ring with thick walls and firing openings directed at the surrounding ditch. Underground passages connect the inner spaces, allowing movement between positions while staying protected below ground.

The caponier was built in 1843 as part of a broader effort to modernize the fortifications of Mainz, at a time when many European cities were rebuilding their defenses using new engineering methods. Over the following decades the military use of the ring faded, and the structure eventually came under heritage protection.

The name comes from the Malakoff tower at Sevastopol, captured in 1855 during the Crimean War, and was given to this work the same year. From 1863 the Hessische Ludwigsbahn owned the building and used it as housing for poor residents. Today it serves as the bar of the Hyatt Regency hotel, and its name carries on in the Malakoff-Terrasse square and the Fort Malakoff Park business centre.

Access to the site is not guaranteed on any given day, as it sits within a hotel complex and visits typically take place through guided tours. Checking ahead before making the trip is strongly recommended to avoid arriving at a closed entrance.

The caponier's name comes from the Crimean War of 1855, not from its shape: it was named after the Malakoff tower at Sevastopol. In 1863 the building passed from the fortress administration to the Hessische Ludwigsbahn, which used it as housing for poor residents. Today it serves as the bar of the Hyatt Regency hotel, and its name lives on in the surrounding Malakoff-Terrasse square and the Fort Malakoff Park business centre.