Allowing humans and fish alike to migrate from freshwater to saltwater and back again.

This former coal gasification plant found a curious second life as a popular public park.

Old submarine parts have been converted into faux whale fins.

A giant Troll lurks under one of Seattle's oldest bridges.

This controversial depiction of the "Founder of California" looks as though it was sculpted from mashed potatoes.

Thousands of turbines whir at at the origin of North American wind power.

A decommissioned Naval base now rents itself out for people who want to blow stuff up.

A massive volcanic plug is now a protected area that hosts a number of bird species.

A 90-acre park on former landfill that hosts an annual kite festival.

This giant temperature attraction created some giant electric bills.

A 1920s speakeasy that had rum runners racing up and down the shores of California.

Elephant seals and sea lions have turned the abandoned buildings on this island into their endangered love shack.

A New England-style lighthouse along California's beautiful Highway 1 gets a re-do.

One of the largest free-standing structures ever built, this dirigible hangar is now simply a giant skeleton.

The graffiti-covered remnants of a former triangulation station are balanced precariously on this California peak.

The most isolated mailbox in America lets desert travelers record their passing.

The headquarters of a secretive order is also a beautifully-designed park.

In the middle of the desert, miles from any human life, sat an anomalous pay phone that still magically answers your calls.

A burnt orange monolithic dome structure perched on a hillside near Interstate 280.

After starting as a whimsical tourist attraction that eventually found its way to ruin, these renovated canals offer a lush and exotic locale on the Pacific Coast.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

Along a California highway is a kind of Jurassic Park made of metal.

This naturally heated mountainous creek has created a group of neon blue pools of potentially deadly boiling water.

The lowest point in North America is home to an undrinkable pool surrounded by fields of geometric salt flats.