The USA
New York   
Washington
Philadelphia
Boston

Russia
Moscow   

Sweden
Stockholm 

China 
Beijing   

France
Paris   

Great Britain
London

The Netherlands
Rotterdam
Amsterdam

Belgium
Brussels

Spain
Madrid
Bilbao

Italy
Rome
Milan
Genoa

Germany
Wuppertal
Köln
Düsseldorf

Switzerland
Zurich

Austria
Vienna

Ukraine
Kharkov

United Arab Emirates
Dubai

Argentina
Buenos Aires

Dominican Republic
Santo Domingo

Puerto Rico
San Juan

Moscow became the capital of Russia and the Soviet Union after the revolution of 1917. Then it had 1.7 million inhabitants. Today the city has more than 9 million inhabitants and about 1000 km2 (40 km from one side to the other). In 1932 construction of Moscow's metro began as a piece of art with elegant and huge stations. Today the Moscow metro seems to be the busiest in the world, carrying an average of 8-9 million passengers on a normal weekday, i.e. some 3,000,000,000 a year.