Cheyenne Mountain's main entry--already deep inside the mountain--has two blast doors like this. It's easy to see, from the thickness of the doors, that the installation was meant as a fortress against enemy attack.Click here for the entire Road Trip 2009 package.
June 27, 2009 6:00 AM PDT
Photo by: Daniel Terdiman/CNET
| Caption by: Daniel Terdiman
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