industrial town, Haut-Rhin département, Alsace région, northeastern France, located in the plain of Alsace between the Vosges and Jura mountains. Situated on the Ill River and on the Rhône au Rhin Canal, it lies 12 miles (19 km) southwest of the Rhine River and 21 miles (34 km) northwest of Basel, Switz. Mulhouse, first mentioned in the 9th century, became a free imperial city in 1308. It entered into defensive alliances with the Swiss in the 16th century. In 1798 it joined the French Republic. It passed to Germany after the Franco-German War (1871) and was reunited to France in 1918. Its most noteworthy ancient building is the 16th-century Hôtel de Ville (town hall), covered with mural paintings. A reproduction of the Klapperstein, the evil gossips' stone, hangs on the southwest facade; the original Klapperstein, now in the historical museum, is a stone weighing more than 25 pounds (12 kg), which was hung around the necks of malicious prattlers on fair days, a practice that persisted until 1781. The 19th-century Protestant Church of Saint-Étienne has its original 14th-century stained-glass windows. The restored 13th-century St. John Chapel, built by the Knights of Malta, has notable wall paintings.

The growth of the local textile industry was responsible for the town's subsequent prosperity. Other industries, such as the manufacture of armaments and railway rolling stock, grew from this base. From the beginning of the 20th century, potash mining developed on a large scale to the north around Wittenheim. Toward the end of the 20th century Mulhouse was faced with the substantial decline, first of the textile industry and then of potash extraction. Efforts to develop new industries centred on industrial zones adjacent to the Rhine (Ottmarsheim-Chalampé) and on the outskirts of the town, notably to the east (Île-Napoléon). New industries include automobile assembly, electronics, chemicals, and plastics. Recent economic growth has concerned primarily the tertiary sector and includes the expansion of the University of Upper Alsace and the development of a science park. Several museums attest to the town's industrial past and contribute to the growth of tourism. Pop. (1999) 105,709; (2005 est.) 106,311.