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

The seamy, underground secrets of Portland's criminal past.

This lower Manhattan bar is set up in an old bank vault that rests beneath a skyscraper that hides even more historic splendor.

The haunting "Hell House Altar" is one of the few remnants of an abandoned college that has been a magnet for local legends.

The world’s oldest and biggest bookstore stocking only mystery, crime fiction, espionage, and thrillers.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

A trash dump made beautiful by nature's power.

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

The United States Capitol's former columns still stand.

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

America's most famous piece of self-built architecture.

These remote Florida islands have a history of sea turtles and sunken treasures, and one of the world's largest coastal brick fortresses.

This whimsical Oz-themed park had a wonderful impact on the surrounding neighborhood.

A walk through the historic city center, under the streets of Seattle.

One man has carved a number of natural New Mexico caves into psychedelic sandstone temples.

A miniature rainforest is growing inside of a Midtown Manhattan office building.

Under the right circumstances, this waterfall in Yosemite briefly turns a luminescent fiery orange.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

A roaring, awe-inspiring double cascade of icy water flows through woodland Oregon like something out of a Tolkien novel.

A layered tribute to the work of mosaicist Isaiah Zagar.

The oldest family-run luncheonette in New York, last renovated in 1948, still serves food and drinks the old-fashioned way.

Elevated freight railway turned wildly successful urban park.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

Try not to get slimed in Tribeca.