[2] A polycentric conurbation with several major urban concentrations, the region covers an area of 7,110 square kilometres (2,750 sq mi), entirely within the federal state of North Rhine-Westphalia.

The Rhine-Ruhr metropolitan region spreads from the Ruhr area (Dortmund-Bochum-Essen-Duisburg) in the north to the urban areas of the cities of Mönchengladbach, Düsseldorf (the state capital), Wuppertal, Leverkusen, Cologne (the region's largest and Germany's fourth largest city), and Bonn in the south.

The metropolitan area is named after the Rhine and Ruhr rivers, which are the region's defining geographical features and historically its economic backbone.

The largest cities in the Rhine-Ruhr area are Cologne, with over one million inhabitants, followed by Düsseldorf, Dortmund and Essen, each of which has slightly more than 580,000.

Historically, most of the Ruhr area was for the most part characterized by heavy industry since the age of industrialisation in the late 19th and early 20th century.

[17] From within, Düsseldorf, Essen, and Cologne are by far the largest economic centers,[18] with specialisation in financial/high tech and insurance/multi media services respectively.

The rail, S-Bahn, U-Bahn and bus companies are administered through a consortium of local and regional transport lines, the Verkehrsverbund Rhein-Ruhr.

Some excursions, theatre and opera tickets as well as museums offer free transportation from any point in the Rhine Ruhr area to the venue and return.

Cologne Cathedral, Augustusburg and Falkenlust Palaces at Brühl and the Zollverein Coal Mine Industrial Complex at Essen are UNESCO World Heritage Sites.