Once described as the "Eagle's Nest," this ruined ancient city rests on a remote mountaintop.

Rivers of cattle blood gone, a strange Escheresque building remains, the last of its kind.

This dangerous-looking suspension bridge may have been too unstable to remain open.

This demolished goliath of American industry once loomed over the depressed town it once made thrive.

One of Chile's most active volcanoes is riddled with beautiful caves.

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

An ethereal glowing blue ocean cave in Croatia.

Formerly Yugoslavia's "forbidden island," this sleepy little city still holds the abandoned remains of military strongholds.

Remote, volcanic island that Darwin, Hooker, and the Royal Navy shaped into a thriving, artificial ecosystem.

The rocks in this arid basin leave trails of movement behind them.

Bolivia's needle-like rock formations.

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

A seemingly endless landscape of pure salt stretches far across Bolivia.

On the outskirts of a desert trading village high on the Andean plain, steel giants have been destroyed by salt winds.

The remains of diamond fever taken over by the desert.

An abandoned stretch of highway, deteriorating next to the operational one.

An Alaska livestock farm devotes itself to harvesting wool from creatures that once ran with mammoths and sabertooth tigers.

Ancient pueblos built into the base of a natural canyon wall.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

A total of 999 stairs lead visitors through a massive hole in a mountain known as the Gateway to Heaven.

An abandoned saucer-shaped monument in the Bulgarian mountains.

The Jesus tree of Malta bears a striking resemblance to Christ on the cross.

One of the most remote and isolated villages on the Arabian Peninsula.

Cretean quarry suggests real-life site for ancient Greek myth of the man-eating Minotaur in his labyrinth.