Fort d ' Aubin - Neufchâteau The Fort of Aubin - Neufchâteau ( ) is a Belgian fortification located near Neufchâteau . The fort was built in the 1930s as part of the fortified position of Liège , augmenting the twelve original forts built to defend Liège in the 1880s with four more forts closer to the Belgian frontier with Germany . The fort surrendered to German forces in the opening days of World War II , following the dramatic assault on Aubin - Neufchâteau ' s sister fort , Fort Eben - Emael . Aubin - Neufchâteau has been preserved and may be visited by the public . Situation . The fort is to the south of Eben - Emael and north of the Fort de Battice in the line of the four 1930s forts , located about east of Liège . Aubin - Neufchâteau and the Fort de Tancrémont are smaller than Eben - Emael and Battice . Collectively , the line was known as the Fortified Position of Liège I ( " Position Fortifiée de Liège 1 " ( PFL I ) ) , the original Liège forts constituting PFL II . Description . The roughly triangular Fort d ' Aubin - Neufchâteau was a development of the original Belgian fortifications designed by General Henri Alexis Brialmont before World War I , a relatively compact ensemble of gun turrets and observation posts disposed on a central massif of reinforced concrete , surrounded by a defended ditch . This was in contrast with French thinking for the contemporary Maginot Line fortifications , which were based on the dispersed " fort palmé " concept , with no clearly defined perimeter , a lesson learned from the experiences of French and Belgian forts in World War I . The new Belgian forts , while more conservative in design than the French " ouvrages " , included several new features as a result of World War I experience . The gun turrets were less closely grouped . Reinforced concrete was used in place of plain mass concrete , and its placement was done with greater care to avoid weak joints between pours . Ventilation was greatly improved , magazines were deeply buried and protected , and sanitary facilities and general living arrangements for the troops were given careful attention . With Tancrémont , Aubin - Neufchâteau was among the smaller of the new Belgian forts , armed with a maximum gun caliber of 75mm . These guns did not have sufficient range to provide mutual support between neighboring fortifications . The Fort d ' Aubin - Neufchâteau comprised several combat blocks surrounded by a defended ditch . Only the tops of the blocks were visible , with the majority of the fort sunk into the ground . The fort also included counterscarp positions , C . I , C . II and C . III , arranged to fire along the ditches with 47mm guns , machine guns and grenade launchers . Block C . III , located just outside the perimeter at the entry , possessed a searchlight and cupolas or cloches for 47mm anti - tank guns . Block B . O . was an air intake and emergency exit , while Block B . P . was the peacetime entry block . Both were located some distance to the west of the defended perimeter , with the underground barracks , magazines and utility plants located between them and the main fort . The approximately of subterranean galleries were buried between and below the surface . A Block K existed purely as a decoy . Personnel . In 1940 Aubin - Neufchâteau was commanded by Commandant - Captain d ' Ardenne of the 3rd Battalion of the Liègeois Fortress Regiment , commanded by Major Herbillon . History . The Fort d ' Aubin - Neufchâteau ' s construction started in April 1935 and was mostly complete at the time of the invasion in May 1940 . At the time of the invasion the fort was commanded by Captain - Commandant d ' Ardenne . Aubin - Neufchâteau fired on German forces on the opening day of the German attack on Belgium , 10 May 1940 . By the end of the day the fort was surrounded , enduring heavy artillery and aerial bomb attacks , as well as infantry assault . The fort sustained heavy damage to its surface installations and the Germans entered the perimeter on 15 May , but did not take the fort . A 20 May assault was held off with help from the Fort de Battice . Another assault the next day brought the fort ' s surrender , as it was nearly out of ammunition . There were significant casualties on both sides during the battle . The fort ' s garrison was taken by the Germans to Königsberg in East Prussia for five years . During the German occupation the fort was used for bunker buster bombs testing like the Röchling shell , causing major damage . The Belgian Army , whose property the fort remains , decided to leave the damage rather than attempt to restore it in 1989 . Present day . The fort is preserved and open for public tours . It remains the property of the military . The fort is home to a colony of bats . A memorial to the 24 dead is located nearby .