The nation's second-ever First Lady urged the founding fathers to "remember the ladies."

This small shop walked so America could run on Dunkin'.

This mill played a key role in the region’s development and it is just one of ten along the east coast of the United States.

The ruins of one of the first railroads in the U.S. lie hidden within a neighborhood cul-de-sac.

The hill that gave the Massachusett tribe, and later the state, its name.

This clock tower is all that remains of Bird Hall, constructed by one of the founding families of this Massachusetts town.

The sprawling, eccentric estate of Ames and Ames, a brilliant botanist, and a genius inventor and artist.

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

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

After James Madison's death, his wife and former First Lady Dolley Madison lived in this yellow building near the White House.

The grand marble structure next to the White House is Andrew Carnegie's temple to Pan-American diplomacy.

The most magical part of this Latin American and Caribbean art museum is a room covered in beautiful blue tiles from floor to ceiling.

A derelict bit of infrastructure from the canal that once ran through D.C. is landlocked in the heart of the city.

This mysterious structure by the Washington Monument is a flood barrier designed to protect the White House against rising waters.

On the Fourth of July this area will transform into a Pompeii-like storm of falling embers and ash.

A gift from Japan, 17th-century lantern stands among the cherry trees at D.C.'s Tidal Basin.

The only National Monument ever to go missing for nearly 50 years then resurface in a dump.

Resonating tubes make music from highway overpass.

This abandoned neighborhood is now a park filled with beautiful trees, wildflowers, and hints of its past.

Naturally formed white marble arch housed in an abandoned marble quarry from the 1800s.

Stay at this storybook estate, featuring Sir Henry Hudson Kitson's masterpiece "Gingerbread House."

The highest point in Tennessee, Clingmans Dome bears witness to the ravages of one type of insect.

The remains of a community that was forced to move for a dam that never materialized still rot in this Pennsylvania park.

This roadside wonder is as mysterious as it is beloved.