A listing of the twenty largest cities in the world, based on population of the entire urban area from 2007 data.

A listing of the twenty-two largest urban areas in the world, based on United Nations estimates, from your About.com expert Guide to Geography.

Refer to this list to learn which cities are the largest metropolitan areas in the European Union.

Largest Cities of the European Union: Refer to this list to learn which cities are the largest in the European Union.

A listing of the largest and most populous urban areas in the world, based on gross metropolitan urban agglomeration population.

A listing of the thirty largest metropolitan areas, with total population, in the United States, from your About.com expert Guide to Geography.

The largest city of the world over the last five thousand years along with lists of the ten largest cities for the years 100, 1000, 1500, 1800, 1900, and 1950.

A listing of the largest and most populous cities in the world, based on metropolitan urban agglomerations population.

The twenty largest cities in the United States based on population.