A Byzantine-era church hidden in a wooded area below the Acropolis.

These caves secretly held national treasures during World War II.

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

This tile-work piece featuring a chicken riding in carriage is both a remarkable artistic creation and a social commentary of politics and culture in 17th-century Portugal.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

A hidden three-foot-wide house separates these two regal churches.

This giant sculpture made of trash is a critique of society's wastefulness.

A perfectly circular lake is formed by the crater of an ancient underwater volcano.

Europe's oldest still-operational tea farm also boasts a spectacular view.

This abandoned five-star hotel is now a five-star urban exploration destination.

As the highest point in the Mid-Atlantic range this stratovolcano offers spectacular views.

Bits of flat terrain surrounded by cliffs make one of the most beautiful landscapes in the Azores.

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

Subterranean place of worship in Indonesia.

Hundreds of Buddhas in a re-discovered Indonesian temple.

This massive complex is made up of hundreds of smaller temples that date back to the ninth century.

Of five volcanoes located in the massive Tengger caldera, this cone is the youngest and most active.

Think you have a tough job? Try carrying 200 kilos through a cloud of sulfur down the side of a volcano.

This tiny lake temple dedicated to a water goddess seems to float on the surface.

Hindu temple of the dead home to hundreds of long-tailed macaques.

The name of this ancient Indonesian temple translates as "Elephant Cave" but it could be more accurately called "The Hellmouth."

One of the holiest places in the region, devotees come to Tirta Empul to bathe in the holy spring water.