One-of-a-kind museum inside the first Boeing 747-400 ever made.

A bizarre roadside attraction and the first instance of miniature golf in the world.

Tour the sci-fi-esque reality of governmental disease management.

Orr Park's dead trees have been carved into a menagerie of whimsical visages.

One person's lost luggage is another person's treasure.

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

A Civil War fort in the middle of Washington, D.C. has been swallowed by a forest.

A rotating cast of guys and dolls in front of a Washington, D.C. building.

A nostalgic bibliographic gem.

This lonely waterfront memorial to the men of the Titanic was erected by the "Women of America."

People escaping slavery may have hidden inside a corpse vault.

The country's oldest continually-operated mini golf course lies hidden in plain sight, eclipsed by one of D.C.'s most popular tourist attractions.

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

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

One of the dwarven trees dates back to 1625 and survived the Hiroshima bombing.

The United States Capitol's former columns still stand.

The singer, actor, and activist lived here during his final years, and now it’s a museum dedicated to his legacy.

A layered tribute to the work of mosaicist Isaiah Zagar.

World's first "penitentiary," meant to be humane, drove men insane.

This meticulously extracted nervous system allegedly came from a 19th-century custodian who donated her body to science.