Pete McBride went through eight pairs of shoes over 13 months, hiked through four sprained ankles, two broken fingers and lost two girlfriends as he and a friend hike the length of the Grand Canyon to save it. The result is a movie and book.

Discover 100 of America's most captivating natural and historic treasures, all incredible sites entrusted to the National Park Service. 

As the National Park Service turns 100, renowned filmmaker Ken Burns talks about the presidents and the parks they protected. 

Often called "America's best idea," creation of the world's first national park at Yellowstone wasn't intended to be a radical new idea by a young nation.