An island in the middle of a lake, in the middle of a volcano, in the middle of a bigger lake, in the middle of a bigger island, in an archipelago, in the Pacific Ocean.

The largest underground church in Europe.

A marvel of Byzantine engineering under the streets of Istanbul.

Beijing's version of Disneyland, completely abandoned, mostly destroyed.

Every autumn, this hillside is ablaze with red summer cypress.

The feral felines of Roosevelt Island have a small army of allies and an abandoned hospital all to themselves.

A remote coral island with a gristly history of shipwreck, battles, and a horrendous war crime.

Remote Honduran Islands with a colorful history.

This elaborate Byzantine-style building was designed for a not-so-pretty purpose.

Hidden beneath the streets of London is a secret subway that only carried mail.

Abandoned landscape once home to "the world's largest winery."

Millions of glowing microscopic organisms light up the waters of this luminous lagoon.

One of the final concrete ships built before World War II is now a crumbling breakwater.

Submerged trees jut ghost-like out of an idyllic turquoise mountain lake.

A millionaire's abandoned swimming pool from the gilded age of one of America's most distinguished families.

These azure waters were thought to lead to the Mayan Underworld.

An ethereal glowing blue ocean cave in Croatia.

The abandoned Japanese amusement park once loomed as a dystopian Disneyland.

Where giant ships go to die.

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

A submerged village appears when dam levels drop.

The longest continuous lava tube in the continental U.S. offers 2.5 miles of dark explorations for the adventurous.

Site full of incredible prehistoric paintings and archeological findings.

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