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, including an air filtration system for protection against gas attack, magazines were deeply buried and protected, and sanitary facilities and general living arrangements for the troops were given careful attention. Eben-Emael and Battice featured 120 mm and 75 mm guns, giving the fort the ability to bombard targets across a wide area of the eastern Liège region. Fort Eben-Emael occupies a large hill just to the east of Eben-Emael village (now part of Bassenge) and bordering the Albert Canal. The irregularly-shaped fort is about in the east-west dimension, and about in the north-south dimension. It was more heavily armed than any other in the PFL I. In contrast to the other forts whose main weapons were in turrets, Eben-Emael's main weapons were divided between turrets and casemates. The 60 mm, 75 mm and 120 mm guns were made by the Fonderie Royale des Canons de Belgique (F.R.C.) in the city of Liège. The artillery turrets were so well-designed and constructed the artillerists were not required to wear hearing protection when firing the guns. Block B.I – entrance block with two 60 mm anti-tank guns (F.R.C Modèle 1936) and machine guns. Blocks B.II, B.IV and B.VI – flanking casemates located around the perimeter ditch to take the ditch in enfilade with two 60 mm guns and machine guns. Block B.V – similar to II, IV and VI, with one 60 mm gun. Cupola 120 – one twin 120 mm gun (F.R.C Modèle 1931) turret, with a range of 17,5 km. There were also three dummy 120 mm turrets. Cupola Nord and Cupola Sud – each had one retractable turret with two 75 mm guns (F.R.C Modèle 1935), with a range of 10,5 km. Visé I and IÍ – each house three 75 mm guns, facing south. Maastricht I and II – each house three 75 mm guns, firing north in the direction of Maastricht. Canal Nord and Sud – were twinned blocks