Two thousand feline artifacts fill Malaysia's "Cat City."

One of the largest caverns in the world has a maw large enough to stack cathedrals in.

These jagged limestone blades cut out through the canopy of the jungles of Borneo.

Two women with a flair for both adventure and artful clutter created this singular round home.

These medieval tunnels provided water to the city above through centuries of civil war and plague.

This historic Benedictine monastery brews a booze so toxic that it has often been blamed almost singularly for Scottish hooliganism.

Two dozen pinball games hidden away inside a most unlikely location.

An abandoned Gold Coast-era mansion once intended for the exiled ruler of Albania, who never arrived.

This beautiful building in the heart of Manhattan's Financial District was empty for decades.

A tiny museum housed in a New York freight elevator specializes in the "overlooked, dismissed, or ignored."

La Monte Young and Marian Zazeela's "Dream House" will immerse you in an ever changing world of sound and light.

Immortal combat in a Moscow museum.

Every May, townspeople welcome summer with a bizarre pagan parade led by a man wrapped in garlands.

This tallest folly in the world began its life as an elaborate factory chimney.

This 1,400-year-old abbey was once a powerhouse for music and intellectualism known across Normandy.

Now famous as the "Harry Potter bridge," this impressive concrete viaduct has long been an icon in its own right.

Crumbling pyramids and temple ruins stand within the shadow of this sacred butte.

Built by crowdsourcing, this wooden foot bridge saved a part of Rotterdam that was languishing in wait of city funding.

A quirky house created entirely out of glass bottles combines a collector's spirit with an artist's flair.

Wind power station for making famous Ketel One vodka.

Unchanged for centuries, this medieval library keeps its books in chains.

A 'living museum' in Leiden, the oldest of its kind in the Netherlands.

Tucked away in the Leiden city hall are a group of works by famed artist MC Escher.

The world's oldest Jewish library was founded by Sephardic Jews in 17th century Amsterdam.