This June 15, 2012 photo released by the National Geographic Visitor Center at Grand Canyon shows an unidentified visitor examining the sidewalk artwork "Grand Canyon Illusion" by artist Kurt Wenner ... more 
This June 15, 2012 photo released by the National Geographic Visitor Center at Grand Canyon shows an unidentified visitor examining the sidewalk artwork "Grand Canyon Illusion" by artist Kurt Wenner outside the National Geographic Visitor Center at the South Rim of the Grand Canyon near Tusayan, Ariz., in this handout photo made on June 15, 2012. The 3-D piece gives the illusion of being perched atop spires and starting down a winding trail that seemingly plunges into the depths of the massive gorge. (AP Photo/National Geographic Visitor Center at Grand Canyon, Joel Kramer) less 
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Associated Press | Photo By National Geographic Visitor Center at Grand Canyon, Joel Kramer
Mon, Jul 16, 2012 12:02 PM EDT