No one's quite sure why there's a metal megaphone bolted on two rocks in the middle of the Mojave Desert.

One lonely, modern pyramid has gone from corporate think tank to deserted boondoggle.

A regular looking rock with an unbelievable history.

A ghost town in a remote corner of Oregon hosts a touching tribute to Sacagawea’s son.

These massive concrete balls were used to mine gold in Virginia.

A massive, secret marina for the Nazis' most formidable weapon in the Atlantic.

The unedited photograph called "Bliss" has graced the screens of over a billion computers.

During World War II, blimps were a key part of the United States' defense against German U-boats—this building could house a dozen of the armed airships.

For decades, vendors have sold clothes once worn by American soldiers who stormed Italy in the 1940s.

An effigy of a trapped paratrooper dangles from a Normandy church to commemorate one remarkable D-Day event.

A grotesque Fiji merman dwells within this traditional Dutch-style building.

One of the oldest surviving Swedish-American homes in the United States.

This local gem houses the largest collection of pre-Raphaelite paintings outside of the U.K.

A blend of art, antiquities, and Americana fill this museum, surrounded by whimsical, enchanting gardens.

This splendid Versailles-inspired mansion has the largest French-style formal gardens in North America.

This 19th century granite fortification is one of the most well preserved forts in New England.

One of the world's earliest skyscrapers.

This magnificent, quirky home sits atop a literal gold mine in the middle of the Nevada desert.

A rugged lava field dotted with molds of the ancient pines that were growing when the volcano erupted.

On the Oregon coast there is a natural hole that seems to be draining the sea.

Two massive rock outcroppings on the Oregon coastline.

This lake in the Cascades lives up to its name, disappearing down a hole every spring.

A volcanic fissure over two miles long and up to 70 feet deep.

Massive crater in central Oregon.