Thought you knew America? Think again. Take a tour of America's UNESCO World Heritage sites -- rich in natural beauty, individual genius and traditions that stretch back 1,000 years.
<b>Grand Canyon National Park</b><br>Come face to face with 2 billion years of history. It took millions of years for the rushing tides of the Colorado River to cut through prehistoric rock, creating the Grand Canyon. Here, at Horseshoe Bend, the Colorado River makes a sweeping U-turn.