This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

The semi-reclaimed ruins of this canal were once part of an ambitious plan to reroute the mighty potomac.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

She stares out across six lanes of traffic, clutching a musket and infant with determination.

FDR's Art Deco hospital tower was hopelessly inefficient.

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

An overlooked memorial honoring the local Washington residents who died in World War I.

Decades before the scandal, this staircase on the river was a literal "water gate."

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

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

A double agent hid information for the Soviet Union beneath this bridge for more than 20 years.

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

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

This simple stone memorial remembers a secret, Geneva Convention-defying interrogation base from WWII.

This unique historical monument features large concrete spheres designed to resemble fallen stars.

Found: Garden of Eden in Miami-Dade County, Florida.

The sign that drew attention to a young boy's cucumber stand is now the name of his fruit superstore.

Stolen goods adorn the organ at Old North Church.

Try not to get slimed in Tribeca.

A remote crossroads honoring a fallen talent.

The whimsical construction on the roof has given rise to many a Montgomery myth about its contents.

The world's smallest park was dedicated in 1948 as the only colony for leprechauns west of Ireland.

A 56-foot tall statue of the god of fire looks out over Birmingham, Alabama.