Under Notger, its first prince-bishop, it grew in importance as a centre of Liège principality and of the Mosan school of art and as a major European intellectual centre. After it was granted a communal magistracy (1185) and citizens' charter (1195), and the guilds were granted representation on the city council (1303), there was a struggle for power between the guilds and the nobles. The nobles failed in a sudden attack, and their armed party was burned to death by the populace in the church of Saint-Martin in 1312, an event known as Male Saint-Martin. Political equality was granted to the labourers and to most of the trade guilds in 1313.

During the 15th-century Burgundian domination of the Netherlands, Liège resisted and was sacked twice by Charles the Bold (1467, 1468). After Charles's death (1477) the city was rebuilt and experienced renewed prosperity in the 16th century under Prince-Bishop Evrard de La Marck. Renewed strife between the prince-bishops and the citizens resulted in the destruction of democratic institutions in 1684. The city was bombarded by the French in 1691 and taken by the English (1702) during the War of the Spanish Succession. A bloodless revolution ended the rule of the nobles in 1789; Liège was annexed to France in 1795 and assigned with the rest of Belgium to The Netherlands in 1815. Its citizens played an important part in the Belgian Revolution in 1830.

After Belgium became independent (1830), the city expanded and became a major industrial centre. Fortified in 1891, it became the main bastion of the Meuse defenses and was occupied by the Germans in both world wars; it suffered heavy aerial bombardment in World War II.

As the commercial hub of the industrial Meuse Valley, Liège developed iron and steel foundries, glassworks, coal mines, armament factories, and copper refineries. It became one of the most important river ports in western Europe and among the largest rail centres in Belgium; its airport is in nearby Bierset. The strong working-class character of the city is reflected in the leading role it plays in Belgian socialist politics. The effects of late 20th-century deindustrialization produced many challenges for the city, particularly high unemployment rates, but the economy rebounded somewhat as the city's service sector expanded.

The cathedral (the former abbey church of Saint-Paul) contains the reliquaries of St. Lambert and Charles the Bold. Among many other Romanesque and Gothic churches in Liège are Saint-Denis, Saint-Jacques, Saint-Martin, Sainte-Croix (containing a gold triptych from 1150), and Saint-Barthélemy, with a baptismal font (1108). The palace of the prince-bishops (built in the 15th century and repaired in the 18th and 19th centuries) is now the Palais de Justice. Saint-Laurent, an old Benedictine abbey, has been a military hospital since 1796.

As the cultural centre of Wallonia (French-speaking Belgium), Liège has concert halls, theatres, an opera, and many fine museums—particularly those of fine arts and of Walloon life, the Ansembourg Museum of decorative art, the archaeological museum (in the Maison Curtius, c. 1600), the arms museum, and the house of the composer César Franck. The state university (1817) was entirely rebuilt in the 1960s on a new site to the south. The Royal Conservatory of Music (1887) is famous for the violin school established by Eugène Ysäye. There are also several national research laboratories and technical schools associated with the major industries of Liège. Pop. (2007 est.) mun., 188,907.