Soldiers were buried next to Lee's house in the center of Arlington Cemetery to dissuade the general from reclaiming his property after the war.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

The unluckiest U-boat in the entire German fleet is now on display in a Chicago museum.

A sculpture made of 10 Cadillacs as a monument to the "Golden Age" of the American automobile.

Dyed by iron oxide over centuries, these sandstone rocks rise thousands of feet into the sky.

Some of the tallest ancient American ruins continue to inspire awe and curiosity.

Limestone caves with spectacular showcase chambers.

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

This water tower slanted at an uncomfortable angle off the old Route 66 was an ingenious marketing ploy.

When you visit his grave, be sure to rub the Great Emancipator's nose for good luck.

When ecosystems collide in the arid Southwest.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

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

Dramatic river bend surrounds a natural red-rocked pedestal.

This Arizona observatory is famous for investigations into Martian life, and as the place humans first spotted Pluto.

A reproduction of earth's many biomes.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

The key to turning shifting dunes into the green oasis of Golden Gate Park.

Concrete strongholds stand guard over the Golden Gate.

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

This extravagant Art Nouveau rest stop features a million-dollar view of the Columbia River.

The longest continuous lava tube in the continental U.S. offers 2.5 miles of dark explorations for the adventurous.

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

The first declared National Monument in the United States.