The World's Ten Biggest Metropolitan Areas

10. Moscow, Russia
Metropolitan area: 13.4 million people
City: 11.3 million people

For the second time in a row, Moscow was named the most expensive city for expatriates in 2007. With more passengers than New York City and London combined, Moscow has the world’s busiest metro system serving more than nine million people a day.

Urban Detail:
Despite Russia’s capital getting richer, its population has been declining due to low birth rates and short life expectancy. (Photo: Reuters)