This quiet park's strange sedimentary spires were named after Kodak's color film.

Berthed at the Charlestown Navy Yard in Boston, "Old Ironsides" is the oldest commissioned warship still afloat.

The site of Paul Revere's historic two lantern warning.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

Look closely and you’ll notice that the color changes a third of the way up the tower.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

A vertically floating hemlock controls the waves and weather at Crater Lake.

The deepest lake in the United States, and once the site of epic destruction that lives on in legends.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

A wild west cemetery in Tombstone, Arizona, provides a window into the Old West.

America's only nuclear missile silo open to the public.

A gothic palace of endless stalagmites and pseudoscorpions waits within one of the world's most beautiful caves.

The longest living non-clonal organisms on Earth.

This crumbling stump is all that remains of what was once thought to be the oldest living organism.

Experience a charming 1930's version of "infotainment."

A Norwegian-born sculptor created these soaring guardian angels at the entrance to Hoover Dam.

The drama of nature in full effect in this Nevada State Park.

This raised bulls-eye visible from space was the subject of an intense geologic controversy.

The fifth-longest natural arch in the world, and the longest outside China.

Erosion and various mineral deposits give this striking canyon its distinct color and soft appearance.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.

The unusual patterns in this rock formation result from two distinct modes of weathering.

A tunnel with windows, so you don't miss out on the impressive views.