A lush indoor jungle fills this bustling Madrid transportation hub.

This park on the outskirts of Rome boasts two ancient Roman aqueducts and a medieval tower.

This beautiful park on the outskirts of Rome protects the ruins of two colossal ancient aqueducts.

This once-booming gold mining hub was basically abandoned overnight.

A startling, centuries-old subterranean marvel hides in plain sight.

The mysterious empty cupola behind the monumental arch points to an ancient prophecy of Delhi.

An ancient iron pillar in Delhi that seems to be rustproof.

An imperial fortress city that incorporated cultural elements from the entire Mughal empire, only to be abandoned the year it was finished.

The world's largest bust sculpture celebrates the Hindu deity, Shiva.

Modest by day, illuminated majestically at sunset.

World's tallest monolithic statue has served as a pilgrimage site since its completion in 993 CE.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

Brisbane's manmade urban beach has enough water to fill five Olympic-sized swimming pools.

The wing of this deserted Boeing 737 almost touches the Dunkin' Donuts next door.

Someone left a Boeing 737 in a field in southern Bali.

A haunting theme park is slowly being swallowed by the jungle.

The name of this ancient Indonesian temple translates as "Elephant Cave" but it could be more accurately called "The Hellmouth."

Some of the world's largest letters are carved into the limestone bedrock of the Nullarbor Plain.

A castle hand-built by a Spanish dreamer in the Australian tropical jungle.

Monument that stands 40 feet and weighs 1,000 pounds.

Fiberglas monument to Moonbi's poultry industry.

Hundreds of stone stairs and a winding medieval bridge connect this haunting Spanish island to the mainland.

Giant topiary dog once played a role in a terrorist bomb plot.

Elaborate tile work in this railway station tells the story of Portugal.