America's largest airports were first farms, golf courses and race tracks

Many of today's airports stretch across vast tracts of acreage that don't hold much interest for anyone but plane-spotters and aviation geeks. But before they housed commercial airports, some of these lands had colorful, non-aeronautical pasts.

Going way back to the last ice age, there's evidence that large creatures roamed the land now occupied by Seattle-Tacoma International Airport.

In 1992, workers digging up earth to make way for Concourse B at Denver International Airport came across fossils of palm leaves, indicating that long before the area became a prairie, it had a subtropical climate.

What is now Minneapolis-St. Paul International Airport was built on the site of an auto race track called Snelling Speedway.