An 18-mile-long tunnel for sewage waste will soon wind within the bowels of Washington, D.C.

A historic cemetery filled with quirky faux wood art and unique tombstones.

A small and somewhat hidden memorial to 68 local veterans of the Vietnam War.

This Georgian-style house built in 1746 is the oldest surviving structure in Bladensburg.

An intricately designed junk art house with four extravagant junk art cars hidden in the suburbs.

The system of air guns are fired off remotely to scare any trespassing avians.

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

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

Remnants of a wall built to separate Black residents of Hall's Hill from a newly built subdivision are a grim reminder of segregation in 20th-century Virginia.

Every drop of D.C. tap water flows through this old waterworks.

The romance of early commercial flight still fills this Art Deco destination.

The remains of a historic plantation nestled in between a parking lot and the rental car return at Reagan National Airport.

Right next to departures—how convenient!

One of the dwarven trees dates back to 1625 and survived the Hiroshima bombing.

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.

The school tested mustard gas for the U.S. Army during World War I.

An extensive, if one-sided, history of U.S. law enforcement's war on drugs.

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

This lovely picnic spot featuring thunderous jet landings is an aircraft spotter’s dream.

Outside the Department of Transportation, a collection of artifacts honors the history of how we get around.

Now a living classroom, this house was once the home of Reverend James Clinton Dent, a formerly enslaved man and a pastor.

Depending on who you ask, this controversial treehouse is either a charmingly creative child's playhouse or an illegal encroachment on public land.

100 years later, they're still down there.