This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

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

One of the only memorials dedicated to journalists who died in combat.

Public opinion is still divided on this enormous sculpture in front of Baltimore's Penn Station.

This bug-eyed water wheel uses the power of the Sun to clean up Baltimore Harbor.

A museum dedicated to exhibiting remarkable outsider art.

It's not hard to see why the historic Peabody Conservatory of Music's library has been described as a "cathedral of books."

A monumental statue of RCA's mascot now sits atop a historical society roof after a life of moving around.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

This beautiful vintage movie palace has seen little change in form or function since the 1920s.

Hidden within an idyllic suburban garden is a memorial dedicated to the victims of a terrifying spree of killings committed on U.S. soil.

South Philadelphia is home to Keith Haring's only surviving in situ collaborative public mural.

This sculpture of a fisherman spent six years at the bottom of the Schuylkill River.

Golden and naked, the figure that was once the highest point in New York is all that remains of the second Madison Square Garden.

Yo, Adrian!

Astounding collection of coin-operated games and automata.

A tribute to the beloved, kind-hearted "homeless mayor" of Silver Spring.

This charming colonial alleyway is one of the oldest continuously used residential streets in the U.S.

An ancient Egyptian obelisk is now used to commemorate fallen Italian soldiers.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

The final resting place of the poets Shelley and Keats.

The skull of the patron saint of lovers lies in the Basilica di Santa Maria in Cosmedin—maybe.

The yawning maw of this pagan visage is said to bite off the hands of liars.

A rare example of a medieval house in Rome adorned with a melancholic inscription.