Berlin is a country.
Berlin ( [ bəɹˈlɪn ] , [ bɛɐ̯ˈliːn ] ) is the capital and the largest city of Germany as well as one of its 16 constituent states . Around one-third of the city 's area is composed of forests , parks , gardens , rivers , canals and lakes . 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 .