Coat of arms of Freiburg im Breisgau, Germany

Freiburg im Breisgau (/ˈfraɪbʊərk ɪm ˈbraɪsɡaʊ/; German: [ˈfʁaɪbʊʁk ʔɪm ˈbʁaɪsɡaʊ] ; Alemannic: Friburg im Brisgau; French: Fribourg-en-Brisgau; lit. Freecastle in the Breisgau; mostly called simply Freiburg) is the fourth-largest city of the German state of Baden-Württemberg after Stuttgart, Mannheim and Karlsruhe. Its built-up area has a population of about 355,000 (2021), while the greater Freiburg metropolitan area ("Einzugsgebiet") has about 660,000 (2018). Freiburg is located at the southwestern foothills of the Black Forest, on the Dreisam River, a tributary of the Elz. It is Germany's southwestern- and southernmost city with a population exceeding 100,000. It lies in the Breisgau, one of Germany's warmest regions, in the south of the Upper Rhine Plain. Its city limits reach from the Schauinsland summit (1,284 metres (4,213 ft)) in the Black Forest to 3 kilometres (1.9 mi) east of the French border, while Switzerland is 42 kilometres (26 mi) to the south. The city is situated in the major wine-growing region of Baden and, together with Offenburg, serves as a tourist entry-point to the scenic Black Forest. According to meteorological statistics, Freiburg held the all-time German temperature record of 40.2 °C (104.4 °F) from 2003 to 2015. An old university town and archiepiscopal seat, it was incorporated in the early 12th century and soon became a commercial, intellectual and ecclesiastical centre for the Upper Rhine region. The University of Freiburg (Albert-Ludwigs-Universität Freiburg), founded in 1457, is one of Germany's oldest universities. Freiburg's main landmark is the Freiburg Minster (Freiburger Münster), which was built between c. 1200 and 1513 and has been described as "Gothic architectural masterpiece". The old town is traversed by an extensive system of runnels called Bächle (lit. small streams), that are fed with water from the Dreisam and run on the side of almost all streets and alleys, giving the city a unique touch. Freiburg has a high standard of living, and is known for its advanced environmental practices, which is embodied by local housing projects such as the creation of the sustainable district of Vauban. The dialect spoken in Freiburg is classified as (Upper Rhenish) Low Alemannic, and therefore most closely related to the other dialects of Baden north of Markgräflerland and south of Karlsruhe, to most dialects historically spoken in Alsace (Alsatian), and to Basel German.