Citadel of Liège The Citadel of Liège was the central fortification of the strategic Belgian city of Liège until the end of the 19th century . It is located in the Sainte - Walburge neighborhood , above the Meuse valley . The first citadel was built on the heights overlooking the city in 1255 . It was rebuilt in a pentagonal shape by Prince - Bishop Maximilian Henry of Bavaria in 1650 . This fortress was destroyed by France shortly afterwards , then rebuilt in 1684 . During the Napoleonic Wars it was given five bastions in the style of Vauban . By the late 19th century the citadel had become obsolete , replaced by the twelve forts of the Fortified Position of Liège . It continued in use as a barracks and as a command post . In the 1970s the citadel was largely destroyed by the construction of a hospital on the site . The southern walls remain . An area on the north side is a memorial to Belgians executed in the citadel by German occupiers in World Wars I and II , while 20th - century bunkers remain on the south side . History . Early history . Around the year 1000 , during the reign of Notker , Prince - Bishop of Liège , the city built its first walls in sandstone . The enclosure was shaped like an elongated rectangle of about , surrounded with a ditch and lined with towers and gates . A gate tower was built at the foot of Pierruse . The first bridge at the site of the Pont des Arches was built around 1033 . In the early 12th century Holy Roman Emperor Henri IV proposed a larger enclosure , but failed to raise the necessary funds . A new wall was started in 1204 from the Porte Sainte - Walburge to Paienporte , then down to the river , and another wall was under construction between the Hocheporte and Sainte - Walburge . In May 1212 the still uncompleted walls were scaled by the troops of Henry I , Duke of Brabant , who sacked the city . Encouraged by this setback , the townsmen completed the walls in 1215 . In 1255 Prince - Bishop Henri de Gueldre built the Porte Sainte Walburga , furnished with towers , a well , a drawbridge and a prison , which was in effect the first citadel on the site . In 1468 the troops of Charles the Bold destroyed the city despite an attack by the 600 Franchimontois . 17th century . In 1650 the Holy Roman Emperor granted Prince - Bishop Maximilien Henri de Bavière obtained permission to build a fort . He erected a large well - protected rectangle , relying on German engineers . The walls were of earthern construction , incorporating the 1548 Sainte - Walburge bastion . However , the construction was blown up by the French shortly after completion . Work began in 1663 on the first permanent masonry citadel . In 1671 work was completed on a pentagonal fortress with bastions at the angles and demi - lunes . On the outer side the walls were lined with ditches , and the citadel was integrated with the city walls . The bastions were named for St . Lambert , St . Francis , St . Mary , St . Maximilian and St . Henry . The Chapel of St . Balbina was placed in the center of the citadel . The French took the citadel in 1675 . In 1676 the French demolished the citadel to prevent it from falling into the hands of its enemies . The bastions , demi - lunes and part of the old ramparts were undermined . In 1684 Prince - Bishop Maximilian Henry of Bavaria began to rebuild the citadel . However , the 1685 Treaty of Versailles , which guaranteed the neutrality of the Liégeoise , required the citadel ' s demolition . In 1691 French troops commanded by Louis François , duc de Boufflers bombarded the city from the vicinity of the Fort de la Chartreuse during the Nine Years ' War . In 1692 the Dutch general Menno van Coehoorn organized the defense of Liège . He established a series of protected trenches on the left bank of the Meuse . This system employed light troops supported by artillery , reflecting van Coehoorn ' s lack of interest in fortifications . 18th century . With the commencement of the War of Spanish Succession in 1701 , the engineer Jacques de la Combe was delegated by Vauban to repair the citadel . In 1702 the engineer Filley reported to Vauban , describing the state of the citadel as lamentable . Vauban came to Liège to try to convince Prince - Bishop Joseph Clemens of Bavaria to underwrite the cost of repairs . In 1702 the allies under van Coehoorn laid siege to the citadel for three days . In 1703 in accordance with the Treaties of Namur and Utrecht , Liège was declared neutral . New work continued from 1707 to 1711 with the addition of new bastions and demi - lunes . The 1713 Treaty of Utrecht established peace between France and the Republic of the Seven United Provinces , followed by the Treaty of Rastatt which settled disputes between France and the Holy Roman Empire , thereby ending the War of Spanish Succession . In 1715 the Treaty of the Barrier was signed at Antwerp between the Empire and the United Provinces , requiring the demolition of the citadel of Liège The bastions and walls on the town side of the citadel remained . 19th century . In 1815 the Dutch took control of the area following the defeat of Napoleon . In 1816 William I of the Netherlands authorized the reconstruction of the citadel to a plan by Camerlingh . In 1817 the St . Balbina chapel , the old Porte Sainte - Walburge and the bastion du Clergé were demolished . The Sainte - Lambert and Sainte - François bastions were rebuilt and demi - lune outworks were added . The Dutch garrison capitulated during the Belgian Revolution of 1830 . The second battalion of the first Belgian Independent Regiment occupied the citadel . In 1891 a royal decree downgraded the citadel and the nearby Fort de la Chartreuse , following the construction of twelve modern forts surrounding Liége . The citadel was used as a barracks . Gallery . 20th century . In 1911 Belgian troops were billeted in the citadel . In August 1914 they participated in the defense of Liège from German invasion . Following the surrender of the city the citadel was used as a place of internment and as a hospital . It continued in use as a hospital following the 1918 armistice . A command post for the Fortified Position of Liège was established in the southern portion of the citade between the warsl , which survives . The rounded concrete forms of the three bunkers contrast with the older masonry . The command post was augmented after World War II with an air intake tower equipped with filters for nuclear , biological and chemical contaminants . Following the Battle of Belgium in May 1940 the citadel was once again used by German forces to intern Belgians . It was occupied by American forces in 1945 , and in 1947 Belgian forces reoccupied the citadel . In 1946 a memorial was established to those who had been executed in the citadel during World Wars I and II . The " Enclos des Fusillés " ( " enclosure of those shot by firing squad " ) was dedicated in 1947 , with 197 crosses commemorating the dead . In 1967 the citadel was turned over to the Public Centre for Social Welfare of Liège , and in 1970 construction of the Centre hospitalier régional de la Citadelle was begun , destroying much of the old citadel . Work on the hospital building started in 1974 and was completed in 1978 . Due to the presence of underground excavations , the hospital was placed on driven piles for support . On 21 December 1977 the fortress and the were listed as classified structures . On 11 October 1982 the bastions and curtain walls were designated , and on 23 March 1988 the walls and the Porte de Païenporte were classified . Bibliography . Jules Loxhay , " Histoire de l ' enceinte et de la citadelle sur la rive gauche de la Meuse , à Liège " , 1999 , 207 p . , Liège , Centre Liégeois d ' Histoire et d ' Archéologie Militaire