This huge abandoned fortress hidden inside a mountain holds a world of subterranean secrets.

A fiery-red region of scooped out land still largely untouched by civilization, tourists or otherwise.

Bacteria and algae give the salty water its bubblegum hue.

An enchanting landscape of ancient sandstone structures eroded into otherworldly shapes.

This abandoned gold mine found a second life as a post-apocalyptic film set.

Spanish architects used seized Muslim gravestones to rebuild parts of the fortress.

Spanning the El Chorro gorge, this pathway used to be one of the most dangerous crossings in the world.

Nestled in the mountains of Portugal is a tiny village made almost entirely of schist.

This gaping hole in the middle of a remote mountain lake looks like a portal to another dimension.

This unassuming chapel in Portugal plays host to a ghoulish collection of bones.

This abandoned naval battery stood at the ready as recently as the 1980s.

Largest cave system in Africa.

This small monument marks the divide between the Atlantic and Indian Oceans at the southernmost tip of Africa.

This African beach is home to thousands of rare mainland penguins that are known for their annoying voice.

This road winds through the steep coastal cliffside offering spectacular views for those who brave the drive.

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

Perhaps the most spectacular grotto along the Algarve coastline.

This small chapel is built of human bones and decorated with a golden skeleton.

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

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

One Portuguese poet described this cape, the westernmost point in mainland Europe, as "where the land ends and the sea begins."

A deer-headed statue that brings together a 12th-century legend and big wave surfing.

An icon of the city, this chapel features an amazing dome ceiling and offers panoramic views.

A tower-like theater in the Swiss Alps built to withstand the high winds and avalanches of the mountain pass.