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

At 207 feet, one of the world's longest continuous escalators.

A home built with marble tombstones from the graves of 2,200 Union soldiers buried in a Virginia cemetery.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

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

This fertility idol of questionable authenticity inspired an iconic Indiana Jones artifact.

The innocent intentions of this monument are somewhat lost in the sculpture's muscled imagery.

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.

This statue of the "father of television" stands prominently in the United States Capitol.

This taxidermy horse was a Civil War hero.

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

The 28,000-year-old specimen is remarkably intact.

Amid the sprawling Defense Intelligence Agency Headquarters is one of Washington's least accessible museums.

The U.S. Navy’s preposterously detailed mini battleship took 77,000 hours to complete.

Part of a WWII submarine is lurking outside the Washington Navy Yard parking lot.

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

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

Look closely and you’ll notice that the color changes a third of the way up the tower.

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

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

One of the largest artillery pieces in the world sits in a Washington D.C. parking lot.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

A little marble compass above George Washington's (empty) tomb in the Capitol marks where D.C.'s four quadrants intersect.

The "lovely red Vega" of the legendary record-settling pilot.