Batterie de Bouviers The Batterie de Bouviers is located in the commune of Guyancourt , Yvelines , France . It is a former fortification built beginning in 1879 and occupied by the army until 1932 . From 1933 it was leased by the Hispano Suiza company as a factory , surrounded by other industrial structures . The site was abandoned by Hispano Suiza in 1990 , and was sold by the Ministry of Defense in 1999 . In 2006 the battery became the " Cafe Musiques " , surrounded by office buildings and a music school . History . In 1870 France was partly occupied by the Prussia n army . Following that defeat , France instituted the Séré de Rivières system of fortifications , with a new outer ring of fortifications to defend Paris from long - range artillery bombardment . 18 forts , five redoubts and 34 batteries were built between 1874 and 1881 . The Batterie de Bouviers was built between 1877 and 1879 as part of this project , near the village of Bouviers in the town of Guyancourt . Since the battery was built the town has expanded with the construction of the Saules neighborhood in the vicinity of the battery . The Batterie de Bouviers was part of an ensemble comprising two forts , the Fort de Villeras in Saclay and the Fort du Haut - Buc , with five peripheral works : the Batterie de la Port du Désert ( destroyed ) , the Batterie de la station de St - Cyr ( partly destroyed ) , the Batterie du Ravin de Bouviers , the Ouvrage des Docks and the Batteries de Bouviers . The Batterie du Ravin de Bouviers is of modest dimensions , and is therefore sometimes termed a redoubt . The similarity between the Battery / Redoubt du Ravin de Bouviers and the Batterie de Bouviers has given rise to confusion between the two positions . The strategy for siting the various fortified positions was one of mutual support between fortifications , with converging fields of fire on enemy troops attempting to pass between fortifications . When conceived in the 1870s the fortifications were considered impregnable . However , the introduction of high - explosive shells capable of penetrating masonry made these positions obsolete almost as soon as they were completed . Description . The principal battery , known as the " caserne sous le parados " ( barracks under the entrance ) is composed of gun chambers all oriented opening on the northeastern facade , with arched vaults expressed on the main wall as blind arches . Materials include limestone , millstone and brick . Concrete was added after 1879 , and was retained in the 2006 renovation . A small bastion protects the entry from direct fire directly opposite the gate . The military battery . The central portion of the battery is composed of rectangular units measuring by , vaulted , and separated from each other by sidewalls in depth , housing the casemates . Individual vaults are structurally independent of the others , preventing damage to one from affecting the others . The casemates are covered by soil up to thick in a trapezoidal mass , using material excavated from the battery ' s dry moat , which surrounds the position . The barracks are served by a corridor to the rear . Doors and windows were fitted with armored shutters , providing protection against shrapnel . Fittings for the shutters remain in place . Two caponier s covered the front of the battery on the far side of the ditch , and another covered the ditch to the rear . The ditch and caponniers have been destroyed , along with the powder magazines . The gate is crowned with the inscription " Batterie de Bouviers " and " 1879 , " with a relief of a mortar on the keystone . Rainwater was collected by gutters and channeled to cisterns under the battery , supporting at least 200 troops and 19 artillery pieces . After the introduction of high explosive artillery shells , the fortifications became obsolete . The forts closest tot eh frontiers were modified , but the fortifications of Paris received little improvement due to financial restrictions . Hispano Suiza . The battery was occupied by the military until 1932 . From 1933 the battery was leased to Hispano Suiza who surrounded it with numerous industrial buildings , where the company made munitions . This caused friction with the local populace , which was until this time predominantly agricultural . Daily test firing caused further concern . At the beginning of the second world war , the battery was bombarded and munitions production was relocated to the Charente . After the war work was confined to work on motors and turbines . The factory was closed in 1990 and sold by the Ministry of Defense in 1999 . Present use . The battery was transformed in 2006 to the " Café Musiques " and opened to the public . The architects were Ivan Franic and Michel Garcin with acoustician Maurice Auffret . Work was sponsored by Saint - Quentin - en - Yvelines . The cafe provides a proscenium stage and accommodations for 450 spectators , three rehearsal and recording studios , technical rooms , dressing rooms and administrative offices , with an adjoining cafe . Work began on the music school in 2008 , designed by architect Yann Brunel . The former industrial lands have been redeveloped . Sodexho France moved its headquarters to the development in 2009 .