One of the steepest streets in the United States makes an intriguing challenge for cyclists.

Mutant vegetables, transgenic mosquitos, and atomic rodents span the walls of this one-of-a-kind museum.

The United States’s oldest funicular railway glides up and down a steep Pittsburgh street.

A stone arch leads to a cavernous 1930s spring house tucked away in the Pennsylvania woods.

The taxidermied remains of Charles Dickens' pet raven, which helped inspire one of Edgar Allan Poe's most famous poems.

Eccentric concrete mansion and museum designed and built by hand from the inside out.

This charming colonial alleyway is one of the oldest continuously used residential streets in the U.S.

Sail through this subterranean show cave that is home to a legend that would go on to name nearly everything around it.

Found art has transformed this Pittsburgh neighborhood into a psychedelic dream.

Mural made of 100,000 pieces of hand blown glass, and until recently, the largest glass mural in the US.

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

House of vintage taxidermy and Steampunk sculptures in a quiet Pittsburgh neighborhood.

Frank Lloyd Wright's most iconic home dangles over a Pennsylvania waterfall.

Philadelphia boasts one of the best — and most often overlooked — traditional Japanese gardens in North America.

Where America's first doomsday cult awaited the end of the world.

Tour the dark and beloved poet's former cobwebbed basement, which may have inspired "The Black Cat."

A rare view of a preserved Victorian science museum.

Hellam Township is reputed to feature seven remote gates, which when passed through in the right order, open an entrance to hell.

Mysterious rocks that ring musically when struck.

A toxic ghost town sitting atop a massive coal fire.

A layered tribute to the work of mosaicist Isaiah Zagar.

An abandoned cemetery lies in ruins as the surrounding forest swallows it whole.

World's first "penitentiary," meant to be humane, drove men insane.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.