In the basement of the U.S. Capitol Building is a hidden storage room full of ornate floor tiles leftover from the 1850s.

The elevator that makes it possible to fly American flags in bulk over the U.S. Capitol

Senators used to relax in the nearly forgotten marble tubs now hidden in the U.S. Capitol Building's basement.

"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!”

During Prohibition, the U.S. Congress had an "official" bootlegger, with his own Capitol Hill office.

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

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

A secret greenspace hides atop a Capitol parking garage.

100 years later, they're still down there.

The discovery site of the "Capitalsaurus," the official dinosaur of Washington, D.C.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

There just so happens to be a court even higher than the U.S Supreme Court: a basketball court in the building itself.

This statue of one of baseball’s greatest pitchers looks like something out of a sci-fi horror movie.

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

The tunnel under the Capitol Building where Congress takes out its trash.

After his presidency, George Washington planned to live only a few blocks from the Capitol building.

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

An unassuming, powerful monument north of the U.S. Capitol bears witness to the resilience of Japanese Americans during a time of grave injustice.

A 1,100-ton train fell through the floor in 1953. Workers got it patched up in just 72 hours.

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.

Railroad officials in the early 1900s sought to spare travelers the sight of Roman soldiers’ private parts.

Need a hardcopy of the 50-title Code of Federal Regulations? This is the place.

Atop this media building, two hives containing more than 30,000 bees keep the surrounding area vibrant.

A historic arena where the Beatles played their first concert in the U.S.