Go inside to really appreciate this 500-year-old technological masterpiece.

Hundreds of thousands of concrete bunkers crowd Albania long after the fall of Communism.

The world's most active stratovolcano is almost always erupting.

The Emperor Tiberius' palace of debauchery.

The glowing blue Nymphaeum of Emperor Tiberius.

A faithful reproduction of Al-Jazari's enormous water clock.

Skyscraper powered by wind turbines attached between its towers.

Lived-in building, bedecked with an astonishing array of mirror mosaics.

The bunker where Hitler took his own life is hidden under this deliberately ordinary parking lot.

Carved fountains poignantly placed in parks and in front of special monuments.

The Guardian of Tallinn.

The world's northernmost aquarium looks like it has fallen over.

Now a hotel, this former bank was the site of a robbery that spawned a psychological phenomenon.

A 1970s resort city now stands abandoned, caught in the middle of a divided island.

Mediterranean castle on a tiny Turkish island.

A New Zealand communications tower stands as the tallest structure in the Southern Hemisphere.

Major tourist destination known for its bubbling mud-pools and hot thermal springs.

A giant Australian fruit and tropical farm.

Alien rock formations grown from the sands of an Australian national park.

Ho Chi Minh's perfectly preserved body has been on display here since 1975.

Ha Long Bay's "Cave of Surprises" houses a popular phallic rock formation.

Teeming with illegal goods and services, this towering maze of vice is also a popular tourist accommodation.

A little sculpture with a large wardrobe.

One of the few standing Roman lighthouses and a labyrinth of tunnels are a couple of the secrets at this historic castle.