A secretive collection featuring objects that were designed specifically for U.S. intelligence operations.

Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.

An astounding collection of medical specimens, including bits of President Lincoln.

A super-sized promotional trick that is now a D.C. landmark.

The United States Capitol's former columns still stand.

Bar full of oddities, specimens, artifacts and homages to the great dime museums of the past.

A tiny piece of the Moon is embedded in this stained glass masterpiece.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

Parking garage where Bob Woodward met Watergate source "Deep Throat."

The "lovely red Vega" of the legendary record-settling pilot.

Giftshop catering to cryptozoologists and anyone with a sense of humor.

America's Most Wanted's set resides in this tribute to the history of crime and punishment.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

Lifelike statue of the Chinese philosopher in the bathtub.

A son-and-daughter meat market, hawked by mom and dad.

China's most famous acrobatics act.

An abandoned set from the 1980 film "Popeye," claimed and repurposed as a theme park by creative locals.

A Hawaiian stairway to heaven—that you can't climb.

Submerged lava formations create incredible waterworks.

A prehistoric landscape hidden in the cliffs of Maha'ulepu.

This former luxury resort in Kaua'i is now an abandoned relic.

This Southern Californian Conservation Center is home to singing and howling apes.

Mined to a depth of 240 meters with a perimeter of about 1.6 km, the largest hand-dug excavation in the world.

An awe-inspiring mosque in Morocco with one of the tallest minarets in the world.