An abandoned marine theme park has created a difficult experiment in dolphin rewilding.

These Australian rock formations look like Martian beehives that have grown up out of the landscape.

Relics of Australia's convict past, and a modern scene of unimaginable horror.

The UFO capital of Australia is the outback’s answer to Roswell.

This pair of Australian "waterfalls" appear to be falling straight across the land.

The labyrinthine storm tunnels beneath the city of Melbourne are ruled by a band of urban explorers.

An opal mining town in the middle of Australia where people live, worship, and shop underground.

The unique ecosystem atop an Australian mountain is home to some colorful inhabitants.

Dilapidated ruins that once treated a notorious young serial killer, currently hosting vandals, squatters, and ghost hunters.

A castle hand-built by a Spanish dreamer in the Australian tropical jungle.

This gracefully curving formation looks like a massive wave that was suddenly turned to stone.

A massive stairway that almost wasn't leads to one of Australia's most scenic vistas.

A well-preserved Ancestral Puebloan ruin tucked beneath a desert cliff.

The now-abandoned tunnels were built for the transcontinental railroad on the route where the first wagon train entered California.

The old fire tower is one of the last of its kind in the United States.

A desert settlement founded and later abandoned by Hawaiian members of the Church of Jesus Christ of Latter-day Saints in Utah's Skull Valley.

This Cold War missile launch site has been abandoned for 40 years.

A partial tunnel blasted into a steep ridge is all that remains of a failed railway across Arizona.

This Old West prison built into the side of a cliff was said to be inescapable.

This former mining hub holds a surprising abundance of undisturbed relics from the Old West.

The crumbling structure is a rare surviving relic of the area's bygone mining industry.

In this century-old literary safehouse, print is alive and well.

An unfortunate geological resemblance to Satan has labeled this Pasadena gorge as a passage to the underworld.

A colorful architectural gem in Seattle's uniquely modern Central Library.