A tunnel dug through the side of a mountain by hand provides convenient yet death-defying access to a small village in China.

Australian Lake set aglow by Noctiluca Scintillans.

The largest cave shaft in the world is home to thousands of birds and popular with BASE jumpers.

An enormous concrete structure built over a nuclear crater.

The world's second-largest excavated hole.

A valley of unique erosion patterns lends to a view like nothing on Earth.

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

Inhospitable caverns just beneath this island paradise offer insights into alien worlds.

An abandoned relic of the city's failed experiment with below ground transit.

A remarkable geological formation resembling a forest made of stone.

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

An abandoned whaling station on an active volcano offers hot springs in Antarctica, surrounded by ruined giants of industry.

This complex of vertically-excavated Buddhist, Jain, and Hindu monolithic temples in India's Maharashtra providence illustrates a spirit of tolerance characteristic of ancient India.

Two churches shoot bottle rockets at each others' bell towers in an unusual Easter celebration.

This iconic fortress was once the crown jewel of Haiti's national defense.

A take-out restaurant that only serves cuisine from countries with which the United States is in conflict.

The Great Wall of Sindh, Pakistan's mighty fort.

A well-preserved network of cavernous tunnels have spent silent centuries removing Toronto's waste.

The third largest ship breaking yard in the world has created an eerie shipping graveyard in southern Pakistan.

Splashes of blue in an otherwise monotonous lunar landscape.

Once an impressive link to Afghanistan’s Buddhist past, now a sad reminder of intolerance towards other cultures.

Eons ago, a rushing lava river formed this pristine passage through solid rock.

A cave's rare beauty held a cavernous secret hidden underground.

Crystal clear lake with a shoreline of travertine located in a Colorado canyon.