This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

Debatably clever, or just plain honest hotel advertised as "The Worst Hotel in the World."

Seven mini rowhouses fill the gap between 54 and 70 Westerstraat.

The site of the famous Nazi book burning campaign of 1933 remembers its "Night of Shame".

The largest free-standing aquarium in the world resides in a hotel lobby in Berlin.

A chinese farmer builds robots from scrap.

This historic Chinese tower was said to have been haunted by fox spirits but is now haunted by a grisly murder.

The former 1920s mansion of a prominent Catalan developer was used as the Soviet Embassy during the Spanish Civil War, and there is still a bunker below the garden.

Step inside the first house designed by Catalan architect Antoni Gaudí, considered to be one of the first Art Nouveau buildings.

Mountain where Jesus was first tempted by the Devil.

This 1920s Amsterdam neighborhood was built as a giant experiment in concrete construction.

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

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

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

Gaze upon chocolate sculptures depicting everything from chariot races to Gaudí's famous church at this shrine to sweets.

This cemetery features modernist statues as strange as its name.

This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

This massive library holds what was once the largest book collection in the world.

The largest cave shaft in the world is home to thousands of birds and popular with BASE jumpers.

Fine dining in the bizarre world of Lewis Carroll.

Hot springs monkey spa in the middle of Hell's Valley.

Designed by Buckminster Fuller, this relic of the 67 Expo survived fire and ice.

Natural cathedral designed by Italian artist Giuliano Mauri.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.