A perfect circle of twenty-four mysterious holes dates back to prehistoric time.

St Bernard de Clairvaux Episcopal Church, better known as one of the oldest European buildings in the Western Hemisphere.

The only swimming pool listed on the National Register of Historic Places is emptied and refilled each day with naturally filtered water.

The oldest continuously operating fish market in the United States.

Also known as the Founding Church of Scientology.

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

Washington's iconic carousel has a nice piece of Civil Rights history.

Before founding the American Red Cross, Clara Barton had a tremendous humanitarian impact by locating thousands of missing soldiers.

Light bulbs, scrap wood, and tinfoil comprise this homemade throne of the gods.

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

It was once the base for a series of domestic terror attacks.

Two dozen pinball games hidden away inside a most unlikely location.

The famous abolitionist’s preserved estate is one of Washington's finest monuments to its great Black citizens.

Housing the National Women's Party since 1929, this historic house is now a monument to the fight for gender equality.

A traveling postal dog covered 48 states and more than 140,000 miles, and he lives on as taxidermy, patched up with a rabbit's foot and a pig's ear.

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

The United States Capitol's former columns still stand.

An FDR-era tuberculosis sanatorium has stood abandoned in the suburbs of the U.S. capital for over 30 years.

A relic of FDR's brief foray into utopian urban planning.

A lovely aquatic park built by a one-armed Civil War veteran who made a fortune from lotuses.

The world's oldest continuously operating airport was founded by the Wright Brothers.

An unusual sculpture, an interesting history, in a strange place, for a good cause.