These pretty kitties killed and ate as many as 135 railway workers.

The New York hotel where tragic visionary Nikola Tesla spent his final hours, destitute and alone but for the pigeons.

The granddaddy of all tourist traps, built on ice water, jackalopes, and a giant dinosaur.

This elaborate towering structure was once famed for its revolutionary height.

A four story, football field-sized, nine-grotto creation made of shells, minerals, and rare stones.

An overlooked monument to the celebrity gangster who helped put the sin in Sin City.

An exotic wildlife habitat right off The Strip.

A terrific purveyor of natural history objects and curios.

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

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

A layered tribute to the work of mosaicist Isaiah Zagar.

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

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

Behind a bodega is a small museum of relics and ephemera showcasing the history of New York.

The world's oldest hologram gallery and the labyrinthine laser laboratory of a holography pioneer.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

One of only two commuter aerial tramways in the United States.

A semi-scholarly approach to sex.

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

Elevated freight railway turned wildly successful urban park.

A crumbling hospital from the 1850s on Roosevelt Island.

The art museum is decorated with creatively remodeled pre-Nazi swastikas.

A Victorian cemetery in the heart of Brooklyn remains a popular mecca of morbid curiosity.

A museum devoted to bringing to light forgotten or neglected histories through exhibitions, education and public programming.