This tea house was a hand-built gift from Boulder's sister city in Tajikstan.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

While not Turkey's deepest underground city, this subterranean redoubt is the largest.

Live a night as a Byzantine King, with a minibar and private jacuzzi.

The highest point in Washington state is a volcano covered in glaciers.

The European towns of Brașov and Râșnov each have proud signs reminiscent of the Hollywood sign.

This solitary monastery may hold the remains of Vlad the Impaler (but probably not).

Romania's triumphal arch looks out over Bucharest.

This palatial botanical garden is home to one of the largest pipe organs ever installed in a private residence, and a piece of Wood's cycad.

Bubbling up from deep underground is the warm crystal clear water that fills the Warm Springs Pools, America's oldest spa.

An ancient tunnel in Jerusalem built to redirect water in the event of a siege is one of history’s great architectural innovations.

Descend 2,030 years into the past in an ancient tunnel built to support Jerusalem's most famous wall.

This trio of Australian rock spires may have inspired aboriginal legend or just modern tourism.

A portly statue of a golden boy commemorates an unusual cause of the Great Fire of London: the sin of gluttony.

An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

A historic ruin just 20 feet away from a busy highway onramp.

This haunted hotel built on natural springs once served as a hospital for a quack doctor promising a cure for cancer.

Climb inside an iron crystal magnified 165 billion times its normal size.

Brussels' favorite peeing boy has a sister.

"Congress may voluntarily remain in session throughout the summer, in order that our Congressmen may be protected from the intolerable discomforts and dangers of the ordinary outdoor weather!”

The world's tallest statue of an American hero.

A giant Troll lurks under one of Seattle's oldest bridges.

The key to turning shifting dunes into the green oasis of Golden Gate Park.

Not merely a museum – but a whirring powerhouse that offers a subterranean peek into the heart and soul of cable car operations.