Fort de Boncelles The Fort de Boncelles is one of twelve forts built as part of the Fortifications of Liège in the late 19th century in Belgium . It was built between 1881 and 1884 according to the plans of General Henri Alexis Brialmont . Contrasting with the French forts built in the same era by Raymond Adolphe Séré de Rivières , the fort was built exclusively of unreinforced concrete , a new material , rather than masonry . The fort was heavily bombarded by German artillery in the Battle of Liège . Boncelles was upgraded in the 1930s to become part of the fortified position of Liège in an attempt to forestall or slow an attack from Germany . It saw action in 1940 during the Battle of Belgium , and was captured by German forces . It is presently abandoned and partly buried , surrounded by housing . Description . The Fort de Boncelles is located about south of the center of Liège , . The fort forms an isosceles triangle whose base is long and whose sides measure . A deep by ditch encircles the fort . The principal armament was concentrated in the central massif . The ditches were defended in enfilade by 57mm guns in casemates resembling counterscarp batteries , firing at shot traps at the other end of the ditch . It is one of the larger forts of Liège . With the exception of the Fort de Loncin , the Belgian forts made little provision for the daily needs of their wartime garrisons , locating latrines , showers , kitchens and the morgue in the fort ' s counterscarp , a location that would be untenable in combat . This would have profound effects on the forts ' ability to endure a long assault . The service areas were placed directly opposite the barracks , which opened into the ditch in the rear of the fort ( i . e . , in the face towards Liège ) , with lesser protection than the two " salient " sides . The Brialmont forts placed a weaker side to the rear to allow for recapture by Belgian forces from the rear , and located the barracks and support facilities on this side , using the rear ditch for light and ventilation of living spaces . In combat heavy shellfire made the rear ditch untenable , and German forces were able to get between the forts and attack them from the rear . The Brialmont forts were designed to be protected from shellfire equaling their heaviest guns : 21 cm . The top of the central massif used of unreinforced concrete , while the caserne walls , judged to be less exposed , used . Under fire , the forts were damaged by 21 cm fire and could not withstand heavier artillery . Armament . Boncelles ' armament included a two rotating Grüsonwerke turrets with two 21 cm guns , a15cm Creusot turret with twin guns and two 12 cm Châtillon - Commentry turret with two guns , all for distant targets . Four retractable 57mm Grüsonwerke gun turrets were provided for local defense . The fort also mounted an observation turret with a searchlight . Eight rapid - fire 57mm Grüsonwerke guns were provided in casemates for the defense of the ditches and the postern , as well as two mobile guns . The fort ' s heavy guns were German , typically Krupp , while the turret mechanisms were from a variety of sources . The fort was provided with signal lights to permit communication with the neighboring Fort de Flémalle across the Meuse and Fort d ' Embourg across the Ourthe . The guns were fired using black powder rather than smokeless powder , producing choking gas in the confined firing spaces that spread throughout the fort . First World War . Boncelles first came under attack on 6 August 1914 . Because the Liège fortifications had proved to be unexpectedly stubborn , the Germans brought heavy siege artillery to bombard the forts with shells far larger than they were designed to resist . Boncelles resisted until the 14th , when it was unable to continue to resist due to the asphyxiating fumes that permeated the fort . In 1915 the Germans undertook an improvement program for the Liège positions , modifying entrances , adding concrete cover and adding metal decking under concrete ceilings . Non - structural improvements included forced ventilation and moving latrines , kitchens and the bakery into the main fort . Fortified Position of Liège . Boncelle ' s armament was upgraded in the 1930s to become part of the Fortified Position of Liège II , which was planned to deter a German incursion over the nearby border . Protection was substantially increased . This was accompanied by improvements to ventilation , protection , sanitary facilities , communications and electrical power . A fortified air intake tower was provided to improve ventilation . Second World War . The fort was bombarded from the air and by artillery in May 1940 by the Germans , killing the commandant , Numa Charlier , and others of the garrison . The fort was taken on May 16 : it did not surrender . The Germans occupied the fort until 1944 , using it as an anti - aircraft position . It became a military depot after the war , and was sold to the commune of Seraing in 1983 . Present . The fort is mostly buried and inaccessible , tightly hemmed in by housing that follows the trace of the former ditch . Only the postern , central massif , air intake tower and two nearby bunkers remain . The site includes a memorial to the dead of World Wars I and II , and a small cemetery . A museum is scheduled to open next to the fort at the end of 2012 .