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

This lovely pocket park is one of the most under appreciated in D.C.

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

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

The national park was once a plantation estate.

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

The oldest continuously operating fish market in the United States.

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

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

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

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

A derelict bit of transportation infrastructure hidden in the woods.

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

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

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.

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

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

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

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

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

This grand gothic brewery has been pumping out suds for over a hundred years.

Home to items never before seen by the public.