Military personnel, federal employees and elected officials take an oath of allegiance or oath of office, but during the American Revolution there was a lot at stake for those who promised "true allegiance to the United States of America"—in writing. One of those historic documents was recently donated to Valley Forge National Historical Park.

When was the last time you tail-gated before a symphony concert? You'll be able to do just that this June at Great Smoky Mountains National Park when the Knoxville Symphony Orchestra helps the park celebrate its 75th birthday.

How much have the national parks changed since you were a kid? Have they changed? When you return to a park that you haven't been to in decades, is it like returning to an old friend, or visiting someplace totally alien?

If you've always thought it'd be fun to hike off into Yellowstone National Park, but just weren't sure you had the requisite skills, here's your opportunity to make it happen.