Gelsenkirchen is the 11th largest city of Germany's most populous federal state of North Rhine-Westphalia and its 262,528 inhabitants make it the 25th largest city of Germany. On the Emscher River, it lies at the centre of the Ruhr, the largest urban area of Germany, of which it is the fifth largest city after Dortmund, Essen, Duisburg and Bochum. The Ruhr is located in the Rhine-Ruhr Metropolitan Region, one of Europe's largest urban areas. Gelsenkirchen is the fifth largest city of Westphalia after Dortmund, Bochum, Bielefeld and Münster, and it is one of the southernmost cities in the Low German dialect area. The city is home to the football club Schalke 04, which is named after Gelsenkirchen-Schalke. The club's current stadium Veltins-Arena, however, is located in Gelsenkirchen-Erle.
Gelsenkirchen was first documented in 1150, but it remained a tiny village until the 19th century, when the Industrial Revolution led to the growth of the entire area. In 1840, when the mining of coal began, 6,000 inhabitants lived in Gelsenkirchen; in 1900 the population had increased to 138,000. In the early 20th century, Gelsenkirchen was the most important coal mining town in Europe.