Fort de la Vitriolerie, Military fortification in Lyon, France

Fort de la Vitriolerie is a triangular fort of Lyon's first defensive belt, with two offensive sides that mounted 66 cannons facing south and east, plus a caponnière and two demi-bastions. Its two-storey barracks housed about 800 men, and a third storey was added in 1860. The entrance wall bears the carved plaque FORT DE LA VITRIOLERIE above grey metal double doors.

Construction began in 1840 under King Louis-Philippe as part of Lyon's initial defensive perimeter. The fort later played a role in regional military operations and eventually became an administrative headquarters.

The fort's name comes from the Vitriolerie, the industrial district that grew up around Lyon's early chemical works. On 4 September 1870, national guards from the city's working-class neighbourhoods stormed the fort to seize its weapons and arm themselves against the bourgeois districts' guards. The site has been called Quartier Général-Frère since 1968, and the name is carved on a plaque above the metal doors of the wall on the Vitriolerie side.

The fort is an active military site, the headquarters of the Terre Sud-Est army region, so the interior is not open to visitors. The entrance on the rue de la Vitriolerie side is marked by a stone surround bearing the carved plaque FORT DE LA VITRIOLERIE above grey metal double doors. The 493 engraved at the entrance is an altitude figure studied by the ASSIL association, not a door number.

A number, 493, is carved at the fort's entrance. A study by the ASSIL association found it is not an altitude in feet above the Saône, as at Fort Saint-Irénée, but a negative height measured from a point at 660 m, perhaps Fort du Mont Verdun (625 m).