Donaueschingen (German pronunciation: [ˌdoːnaʊˈʔɛʃɪŋən] ^ⓘ; Low Alemannic: Eschinge) is a German town in the Black Forest in the southwest of the federal state of Baden-Württemberg in the Schwarzwald-Baar Kreis. It stands near the confluence of the two sources of the river Danube (in German: Donau).

Donaueschingen stands in a basin within low mountainous terrain. It is located about 13 km (8.1 mi) south of Villingen-Schwenningen, 24 km (15 mi) west of Tuttlingen, and about 30 km (19 mi) north of the Swiss town of Schaffhausen. In 2015 the population was 21,750, making it the second largest town in the district (Kreis) of Schwarzwald-Baar. It is a regional rail hub.

Donaueschingen lies in the Baar basin in the southern Black Forest at the confluence of the Brigach and Breg rivers—the two source tributaries of the Danube—from which the town gets its name. This is today considered the true source of the Danube.

An enclosed karst spring in the park of Donaueschingen Palace, the source of the "Donaubach", is known as the source of the Danube.

The municipal area extends continuously from the granite and gneiss of the Black Forest through the Triassic formations of the Schwarzwald-Baar talus to the Swabian Alb, and exhibits all strata of the southern German cuesta country. The heights decrease from 1,020 metres (3,350 ft) in the Black Forest to about 660 metres (2,170 ft) on the Baar plateau, then increase to above the 900 metres (3,000 ft) mark again at the Swabian Alb. A model showing the extraordinary geological setting of the city and its surrounding region is located in the park opposite the train station.

The town is close to Lake Titisee and less than an hour's drive from both Switzerland and France.

Donaueschingen is first recorded as Esginga in 889; the modern form of the name is first attested in 1292. In 1283, Rudolph von Habsburg granted the principality of Baar and Donaueschingen to Heinrich von Fürstenberg. The right to brew beer was also connected with this grant. This is the source of the Fürstenberg Brewery. In 1488, possession was passed to the Count of Fürstenberg-Baar. From the 18th century it was the residence of the Princes of Fürstenberg, who resided in Schloss Donaueschingen. In 1806, Donaueschingen came under the rule of the Grand Duchy of Baden and was granted township in 1810. A large part of the town was destroyed by fire in 1908. Donaueschingen has a tradition as a military garrison; from 1945 to 2014 the French military had barracks in the town, and, until the early 1990s, the U.S. Air Force operated a contingency hospital there. The hospital never received casualties on a large scale from military operations; it saw the most activity in 1989, when the United States offered the facility as temporary housing for refugees leaving from East Germany to the West.

Though the Princes of Fürstenberg were nominally mediatised and deposed as absolute ruler of the principality, they still own huge property in their former lands, including their palace with the surrounding parks and gardens. The Schlosspark (palace gardens) which used to be public and the only park accessible to the citizens of the town since 1806 recently became off-limits again. The Princes of Fürstenberg were also the owners of an important manuscript of the Nibelungenlied (Manuscript C) until they sold it in 2001. The ancestral brewery has also been sold.