Berlin is a city.
Berlin . With a population of approximately 3.7 million , Berlin is the second most populous city proper and the seventh most populous urban area in the European Union . Following German reunification in 1990 , Berlin once again became the capital of all-Germany . Berlin is a world city of culture , politics , media and science . A capital city ( or simply capital ) is the municipality exercising primary status in a country , state , province , or other region , usually as its seat of government .