A painfully obvious spy house sits right across the street from the Russian Embassy.

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

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

An 18th-century townhouse that once hosted guests of the president.

A brass and marble scale model of the solar system embedded in the concrete.

Home to two notable early-20th-century Black educators, Lucy Slowe and Mary Burrill.

Outside the Department of Transportation, a collection of artifacts honors the history of how we get around.

An echo chamber with a waterfall wrapped around its base at the Embassy of Canada in Washington, D.C.

The most accurate timepiece in the world.

An obscure public service from the U.S. government that redeems burnt, moldy, and soiled old greenbacks.

A museum cafe showcases Native American dishes and indigenous ingredients from across the Western Hemisphere.

An Industrial Revolution-era public work that purified water using nothing but sand.

The burning of this 12th-century church kicked off a campaign of Norwegian Black Metal terror.

For 60 years, the academy had no permanent location until members voted Washington D.C. as its forever home.

One of the largest artillery pieces in the world sits in a Washington D.C. parking lot.

This cavern was used as a hidden hospital and safe house during the Vietnam War.

From a neon Rapunzel to a bike traffic meter to a street fair color scheme, the most opened drawbridge in the US is a veritable art gallery.

An enclosed rotunda at the Henry Art Gallery in which viewers can look up and see the uninterrupted sky.

A Museum of Holography frozen in 1974.

Steel remnants of a bridge make up a unique sculpture along the banks of the Illinois River.

An abandoned observatory in the middle of the Illinois prairie.

A long lost multi-cultural music venue used to reside in the bottom floor of Chicago's Flat Iron Building.

Landmark Chicago building narrowly avoided destruction.

A spectacular remnant of an Adler and Sullivan masterpiece that was destroyed in 1972.