Berlin is a place.
Berlin . Berlin in the 1920s was the third largest municipality in the world . Following German reunification in 1990 , Berlin once again became the capital of all-Germany . Berlin serves as a continental hub for air and rail traffic and has a highly complex public transportation network . 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 .