The program does not speculate on how humanity may disappear, stipulating only that it has, and that it has done so suddenly, leaving everything behind including household pets and livestock that have to fend for themselves. The thought experiment is based on documented results of the sudden removal of humans from a geographical area and the results that have occurred when people discontinue the maintenance of buildings and urban infrastructure. Lurie's narration begins: "What would happen if every human on Earth disappeared? "This isn't the story of how we might vanish...it's the story of what will happen to the world we leave behind."

The series' episodes thematically offer examples of urban and biological decay. The focus is on specific locations such as skyscrapers, religious icons, bridges and dams, and government buildings, and the fate of certain related objects, such as artifacts, documents and human bodies. The fate of some kinds of flora and fauna are covered as well. Each episode also contains a segment in which experts examine real locations that have been abandoned by people, including ghost towns and other sites of deterioration, where the deterioration has been caused by events similar to those outlined in the episode. Although the series speculates on the fates of landmarks around the world, the main focus is on situations that may occur at locations in the United States.

The various events that may occur after people disappear suddenly are depicted using CGI dramatizations. Structures covered include the Egyptian pyramids, the Colosseum, the Empire State Building, the Sears Tower (now known as the Willis Tower), the Astrodome, the Space Needle, the Eiffel Tower, the Burj Khalifa, the Golden Gate Bridge, the Gateway Arch, Taipei 101, the USS Constitution, the Hoover Dam, the Sydney Harbour Bridge, Grant's Tomb, John Hancock Center and Air Force One. The time line of predicted events begins approximately one day after the disappearance of mankind and extends up to one hundred million years into the future (one day, one week, one year, 10 years, 15 years, 25 years, 50 years, 100 years, 200 years, etc.).

Tagline[edit]
The program's tagline is the ominous greeting, "Welcome to Earth...Population: Zero."

Ratings[edit]
The two-hour special documentary had an audience of 5.4 million viewers and was the most watched program ever on the History Channel.[2] The program was broadcast in the United Kingdom on Channel 4 and narrated by Struan Rodger on May 29, 2008 and in Australia on Channel Seven on November 25, 2008, edited down to air for 90 minutes, with narration by Australian television presenter Simon Reeve.

The success of the special eventually spawned a spin-off television series, which premiered on the History Channel on April 21, 2009. A second season began airing on January 5, 2010.[3]