Perhaps the most spectacular grotto along the Algarve coastline.

This lonely gas station has stood at this location since 1917.

Under a glass sidewalk lie the remains of some of Manhattan's oldest buildings.

The remote outlaw hideout of Jesse James, Butch Cassidy, and the Sundance Kid.

This apartment is a true time capsule of local life in Bulgaria during the Soviet regime.

An architectural gem nestled into a promontory overlooking a prehistoric landscape.

Also known as "Robin Hood's tree," this tree became a famed location along Hadrian's Wall before it was cut down in an act of vandalism.

A late-night restaurant empire was launched from this humble storefront.

The world's largest collection of materials relating to lesbian history is housed in a Brooklyn townhouse.

A living archive of urban activism and space reclaimed.

The oldest family-run restaurant in the United States is a living museum of New Orleans dining history.

Modern art meets modern convenience in possibly the world's most architecturally important public bathroom.

A magical sinkhole on the Yucatán Peninsula is adorned with mini waterfalls and hanging vines.

This vertical pinnacle in China was the inspiration for the floating mountains in the movie “Avatar.”

Mother Nature outdoes herself with this stunningly beautiful set of caves carved into marble.

These layered sandstone mountains in China look like they are made of pressed crayons.

Romania's "Red Ravine" is a little-known natural wonder that bears a resemblance to the Grand Canyon.

After millennia of erosion by sand and churning water this Brazilian valley now looks like a lunar fantasy.

A long, winding trek rewards you with a gorge so captivating it inspired a painting in the Tate.

Rare recess caves fill this unbelievably beautiful Ohio park.

An ancient Scottish rock formation said to be the gravesite of a giant remains ensconced in legend and intrigue.

This extraordinary geological oddity resembles human-made pavement.

Islanders once used this dramatic, otherworldly landscape to hide their cattle from Viking raiders.

The land is full of geologic eye candy, such as otherworldly spires, mushroom-shaped hoodoos, and prehistoric fossils.