Museum housed in underground tunnels that date back to Buenos Aires's earliest settlements.

A toxic lake near a volcanic caldera that is home to flamingos and other life.

A gateway to a mysterious network of underground tunnels.

Xul Solar was an artist of alternate worlds, inventor of languages, and dreamer of utopias.

A bright little alley in La Boca is a part of tango history.

A tower devoted to — and modeled after — the Divine Comedy.

Stenciled handprints and wall paintings dating back 10,000 years, some of the earliest forms of cave art.

This stunning mass of ice spans 121 square miles and is still growing.

A series of waterfalls so massive they straddle the border of Argentina and Brazil.

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

Ruins of a German Castle on top of a towering stone pillar.

A slice of central Asia in the middle of Berlin.

Started as a kitchen garden, now the second largest botanical garden in the world.

The fairy tale castle of the "fairy-tale king."

A whimsical and twisted animatronic monster tour beneath the streets of Berlin.

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

Leave the wardrobes and sweets to British schoolchildren, Shanghai's got a Coke machine that leads to booze.

9,000 years of carnal history is on display at China's original Museum of Sex.

Beijing's expansive subterranean hiding spot now crumbles away as a tourist destination.

A clay house decorated with ceramic chips in Tianjin.

A collection of cafes and shops all crafted from recycled storage containers.

With former lives as a bomb shelter and government parking lot, this shop is one of China’s most extraordinary locales for book-lovers.

Small Chinese fishing village impeccably maintained for visitors.