A floating cat sanctuary on an Amsterdam canal.

The modern birthplace of Irish freedom.

Former villa and estate of James Deering developed to preserve native tropical forests.

The only swimming pool listed on the National Register of Historic Places is emptied and refilled each day with naturally filtered water.

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

The oldest-known example of a historic architectural style recognized by UNESCO.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

An ancient knight and a symbol of the city's freedom.

This statue once earned the distinction as one of the "Three Major Disappointments of the World."

The highest pedestrian bridge in Singapore looks like a series of undulating waves rising between two public parks.

This Singaporean food-court stall was home to the world's cheapest Michelin-starred meal.

The largest pool at its elevation sits on top of one of the most expensive resorts in the world.

Singapore's landscaping project is home to 18 incredible Supertrees.

Native Australian lizards inhabit this garden celebrating Sydney and its sister city in China.

Come for the flowers, stay for the bats!

Built over an abandoned train yard, this hidden gem is full of winding paths and offers gorgeous views of Sydney Harbour.

Isolated atop this Balinese sea crag is a lovely Hindu temple that is said to be guarded by sea snakes.

One man's love of sea life and art has turned his home into a temple of outsider island art.

This imposing memorial contains the remains of Che Guevara — and 29 other guerrillas who died with him in Bolivia.

His music once banned in Communist Cuba, John Lennon is now immortalized in bronze by Castro, who considers Lennon a "fellow dreamer."

Once a favorite playground for the world's most illustrious guests, Hotel Nacional's secret weapons and bunkers reveal a more menacing side to its golden history.

A focal point of the Cuban government, this city square features one of the most iconic images in the country.

This well held a sacred source of water supposedly unleashed from the barren rocks by a wizard-like archbishop.

A Christian monastery stands on what was once a holy Incan temple.