The floor of this spectacular Baroque sanctuary is covered in memento mori.

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.

The graveyard holding the remains of George Washington's slaves was forgotten for nearly 200 years.

A tiny theater hidden in an alley plays a constant stream of short silent films for anyone willing to peer through the peephole.

Located on 420 acres in the high desert, this spiritual center is dedicated to the "science of the future."

An alternate history park where the Union Army loses the war... to dinosaurs.

The house where John Wilkes Booth conspired with his co-conspirators.

Giant marble phalluses on the sacred island of antiquity.

The world's first interactive human body museum also serves as a chair for a giant orange man.

Art deco landmark on the outskirts of Washington, D.C.

The United States Capitol's former columns still stand.

What looks like a link in Gondor's early warning system is actually a centuries-old Italian fortress.

One of the earliest relics of Italian art is this ornately equipped stone soldier.

Community bookshelf of 25-foot-tall book spines.

This abandoned prison castle has become an imposing gallery of graffiti art.

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

The site of the climactic scene from the classic horror film is now a historic landmark.