This small memorial is almost as well concealed as Smalls himself was on the night he sailed to freedom.

South Carolina's last remaining slavery auction house is now a museum devoted to its own tragic history.

This psychedelic tromp l'oeil seems to be beckoning drivers to crash into a wall.

This titanic steel chain linking two buildings was installed without permission but instantly beloved.

Elevated freight railway turned wildly successful urban park.

Perhaps the world's only gas station inspired by a political scandal.

You might recognize this historic Oregon mansion from its appearance in 'The Goonies.'

This former mining hub holds a surprising abundance of undisturbed relics from the Old West.

The first car-centric shopping plaza in the U.S. brought a little bit of Spain to downtown Kansas City.

A beloved, quirky little fountain featuring a large frog spitting water at a naked boy.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

A little lighthouse in New York City, surrounded by mysterious stories of insanity-driven construction.

There must be a pun in this haystack somewhere...

The one-stop shop for all of your superhero (or evil arch-nemesis) needs.

A commemorative plaque hides a door that leads down to the New York Public Library's underground book bunker.

On this island, you suck away your garbage via an elaborate pneumatic tube system.

Stunningly detailed mosaics in a New York subway station bring life to the Weimaraners of artist William Wegman's work—and to thousands of commutes.

A former insane asylum despised by Nelly Bly and Charles Dickens is now fashionable apartments.

The feral felines of Roosevelt Island have a small army of allies and an abandoned hospital all to themselves.

A Pythagorean funhouse that tries, successfully, to prove that math is the coolest thing ever.

Two large-scale sculptures of Adam and Eve greet visitors in the nude at the Time Warner Center in NYC.

An homage to Jackie Gleason's bus-driving character from 'The Honeymooners.'

Manhattan’s Battery Park has a whimsical carousel full of spinning, glowing fish.

If you look closely at the oldest bridge in Paris, you might notice hundreds of ugly faces leering from its sides.