Ulm (ʊlm) is a city in the German state of Baden-Württemberg, situated on the river Danube on the border with Bavaria. The city, which has an estimated population of more than 126,000 (2018), forms an urban district of its own (Stadtkreis) and is the administrative seat of the Alb-Donau district.
Founded around 850, Ulm is rich in history and traditions as a former free imperial city (freie Reichsstadt). The neighbouring town of Neu-Ulm in Bavaria was part of Ulm until 1810.
Today, Ulm is an economic centre due to its varied industries, and it is the seat of the University of Ulm. Internationally, the city is primarily known for having the church with the tallest steeple in the world (), the Gothic minster (Ulm Minster, German: Ulmer Münster), and as the birthplace of Albert Einstein.
Ulm lies at the point where the rivers Blau and Iller join the Danube, at an altitude of above sea level. Most parts of the city, including the old town, are situated on the northern bank of the Danube; only the districts of Wiblingen, Gögglingen, Donaustetten and Unterweiler lie on the southern bank. Across from the old town, on the other side of the river, lies the twin city of Neu-Ulm in the state of Bavaria, smaller than Ulm and, until 1810, a part of it (population c. 50,000).
Except for the Danube in the south, the city is surrounded by forests and hills which rise to altitudes of over , some of them part of the Swabian Alb. South of the Danube, plains and hills finally end in the northern edge of the Alps, which are approximately from Ulm and are visible from the city on clear days.
The city of Ulm is situated in the northern part of the North Alpine Foreland basin, where the basin reaches the Swabian Alb. The Turritellenplatte of Ermingen ("Erminger Turritellenplatte") is a famous palaeontological site of Burdigalian age.
On the right (south-eastern) side of Danube and Iller there is the Bavarian district town Neu-Ulm. On the left (north-western) side Ulm is almost completely surrounded by the Alb-Danube district.