This unique museum cafeteria showcases the history and regional diversity of African American cuisine.

The unique traffic pattern named for an influential urban planner is also known as the Pedestrian Scramble.

The span is crooked and made from two older recycled bridges.

An easily overlooked memorial to a Ukrainian famine-genocide that killed over 4 million people.

This imposing Masonic temple a mile from the White House was the first public library in Washington, D.C.

Largest Roman Catholic church in North America.

Home to a vast and influential collection of Shakespeareana.

Government testing at the asylum briefly explored using marijuana as a "truth serum" on Nazi prisoners of war.

A Spiritualist house of worship where believers communicate with the dead in the spirit world.

The walls of the iconic dome are hollow and have a secret stairway.

When it opened during the final years of the embargo, all the drinks and cigars were free.

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.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

A derelict bit of transportation infrastructure hidden in the woods.

A three-story tower of books about Abraham Lincoln is one of the more unusual monuments to the president.

Fittingly, America's museum of architecture is itself a magnificently designed old building.

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

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

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

Franciscan monks created a facsimile of the Holy Land for North Americans who couldn’t afford the trip overseas.

A wondrous old library overlooking the nation's capital.

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

A historic neighborhood church is reborn as a psychedelic arts collective.