Copenhagen (English pronunciation: /ˈkoʊpənheɪɡən/; Danish: København is the capital and largest city of Denmark, with an urban population of 1,181,239 (2010) and a metropolitan population of 1,894,521 (2010). Copenhagen is situated on the islands of Zealand and Amager. With around 2.7 million inhabitants within a 50 km radius, Copenhagen is one of the most densely populated areas in Northern Europe.

First documented in the 11th century, Copenhagen became the capital of Denmark in the beginning of the 15th century and during the 17th century under the reign of Christian IV it became a significant regional centre. With the completion of the transnational Oresund Bridge in 2000, Copenhagen has become the centre of the increasingly integrating Oresund Region. Within this region, Copenhagen and the Swedish city of Malmö are growing into one common metropolitan area. In 2008, Copenhagen was the most visited city of the Nordic countries with 1.3 million international tourists.

Copenhagen is a major regional centre of culture, business, media, and science, as indicated by several international surveys and rankings (see International rankings below). Life science, information technology and shipping are important sectors and research & development plays a major role in the city's economy. Its strategic location and excellent infrastructure with the largest airport in Scandinavia located 14 minutes by train from the city centre, has made it a regional hub and a popular location for regional headquarters as well as conventions.

Copenhagen has repeatedly been recognized as one of the cities with the best quality of life. It is also considered one of the world's most environmentally friendly cities. The water in the inner harbour is so clean that it can be swum in, and 36% of all citizens commute to work by bicycle. Every day they cycle a total of 1.2 million km.

Since the turn of the millennium, Copenhagen has seen a strong urban and cultural development and has been described as a boom town. This is partly due to massive investments in cultural facilities as well as infrastructure and a new wave of successful designers, chefs and architects. Copenhagen is ranked as the 7th most expensive city as of 2008.