Petting this mysterious iron monkey supposedly brings good luck.

This is what trains will look like after the zombie apocalypse.

The perfectly named cave drop is the deepest in the continental United States, almost matching the height of Seattle’s Space Needle.

This architectural stunner is one of the few surviving Egyptian Revival theaters in the U.S.

The unusual lighthouse looms over waves of prairies with no sea in sight.

Reaching the "Church in the Sky" requires scaling the cliff face of a sandstone pinnacle with a 650-foot drop.

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

An Art Nouveau gem hides beneath the layers of city grime obscuring this once-magnificent building.

The narrowest house in Buenos Aires is less than 10 feet wide.

The medieval institution is home to the precious treasure stolen in World War II in one of the greatest art thefts of the 20th century.

The weathered grave of a medieval anchoress who walled herself up in a cell attached to a church.

This tiny hotel perched atop a 50-foot tower really puts things into perspective.

An eccentric 18th century naval officer built a ship's quarterdeck on his roof, the inspiration for Mary Poppins's "Admiral Boom."

When it came to designing his own small office building, the eccentric architect wasn't afraid to show the world what he could do.

Perhaps the tiniest sculpture in Saint Petersburg is a little bronze finch inspired by a song.

An enormous playhouse designed to look like 21 stacked Lego bricks, with another 25 million colorful Legos inside.

A deserted hodgepodge of experimental structures designed by nearby university students.

The ancestral home of beloved English poet Lord Byron has a bizarre history.

A blunder resulted in these charming stone-lined streams becoming the target of a Nazi bombing.

This memorial commemorating fallen Swiss Guards of the French Revolution has been called the saddest stone in the world.

The steepest classic funicular in the world glides along a dizzying incline.

An overlooked collection of over 350,000 artistic works created by psychiatric patients using art therapy.

Made from trees and then abandoned, this fence is still growing along a path in Germany.

Locals call it the "Give Peas a Chance" bridge because of its distinct graffiti.