March 13, 2008—Mount Fuji's silhouette looms above the blazing lights of Tokyo's busy Shinjuku district on December 5, 2005.

The Japanese capital is the world's largest and most densely populated city. Its metro region is home to about a fourth of Japan's population.

A UN forecast released last week reports that half of all humans will live in urban areas by the end of the year—and 70 percent by 2050—even though cities occupy only about 3 percent of Earth's land surface.

• See More Photos in the News
• See Today's Top News Stories
• Get Our Free Email Newsletter: Focus on Photography