Last winter, I went to visit some friends in Phoenix, AZ, and couldn't decide how to make the best use of my limited time. One day, since my buddy has to be home by 3PM in order to greet his kids before their return from school, we had to pack a lot into a short day, especially since we'd be spending most of our time in the car.

I found the National Park Service's Web site to be an invaluable resource in planning my trip. One of the gems I saw during my adventure thanks to the site was Montezuma's Castle. Carved into a towering limestone cliff is a 20 room high-rise apartment that provided shelter in an unforgiving desert landscape.