One-time largest man-made structure in the world will be a park in 30 years.

Featuring the the longest lift span of any vertical-lift bridge in the world.

The building that inspired Shirley Jackson's "The Haunting of Hill House."

The Vermont grave of a 4,000-year-old mummy prince.

The remains of a deserted 1800s farming community can be found in Little River State Park.

Antique gaffe kept in the basement of a small Vermont natural history museum.

This "common-as-dirt" museum celebrates the glory of normalcy.

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

A heroic pigeon that, through a barrage of gunfire, delivered a message that saved over 100 lives in World War I.

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

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

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

Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

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

Where the U.S. government kept its actual treasure, before Fort Knox.

Once the supplier for noteworthy projects like the National Cathedral, this old brickworks now lies abandoned.

The only Civil War battle in Washington D.C. took place near this highest natural point in the city.

The national park was once a plantation estate.

Rumor has it the uncarved lump behind the three famous suffragists is reserved for the first woman president.

A computer bug so primitive it was an actual insect.

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

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

Home to a vast and influential collection of Shakespeareana.

"Congress may voluntarily remain in session throughout the summer, in order that our Congressmen may be protected from the intolerable discomforts and dangers of the ordinary outdoor weather!”