Before Metro, Washington had a robust streetcar network—and you see the remains of this infrastructure if you know where to look.

This forgotten boat elevator was an engineering marvel in its heyday.

The oldest building in the District of Columbia was preserved because of a mistaken connection to George Washington.

A much-maligned monument to teetotalism.

This lovely pocket park is one of the most under appreciated in D.C.

An overlooked oasis of quiet on the grounds of Washington's monumental basilica.

The hidden offices underneath Memorial Bridge have been locked up since 1976.

A historic ruin just 20 feet away from a busy highway onramp.

This poor little statue is the most vandalized memorial in Washington.

The most accurate timepiece in the world.

These recently uncovered walls are all that's left of Washington, D.C's first defense contractor.

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

A super-sized promotional trick that is now a D.C. landmark.

People escaping slavery may have hidden inside a corpse vault.

There’s a hidden military meme engraved on the World War II Memorial.

The country's oldest continually-operated mini golf course lies hidden in plain sight, eclipsed by one of D.C.'s most popular tourist attractions.

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

A derelict bit of transportation infrastructure hidden in the woods.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

A monument in Washington D.C. marks the spot from which all other roads were supposed to stem.

The narrowest house in America is seven feet of pure spite.

America's first federal monument.

A memorial to the tens of thousands of Irish who fled to North America during the Great Famine.