A forgotten relic from New York's bygone trolley system hides in plain sight under a bridge.

An Industrial Revolution-era public work that purified water using nothing but sand.

The fanciest public restroom in New York City boasts fresh flowers, art, and a classical music soundtrack.

A layered tribute to the work of mosaicist Isaiah Zagar.

America's greatest forgotten garden and the former stomping grounds of Son of Sam.

The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.

Read between the lines of the subway map to find the hidden abandoned Civil War fort.

The floor-to-ceiling collection in an old factory is a unique alternative to stuffy galleries.

A staggering collection of photographs depicting medical, social, and historical change.

This hulking behemoth is actually five interconnected towers built in the 1960s.

A little stop along the Texas highway where Rock Hudson, Elizabeth Taylor, and James Dean stayed while shooting the 1955 film "Giant."

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

Once in a state of dilapidation, this candy-inspired fortress is now being revived.

Tucked behind New Jersey's abandoned Gingerbread Castle lie the eerie ruins of a once-flourishing paper mill.

Seven golden statues rise into the sky from sculptor Victor Victori's New Jersey front lawn.

A working metal shop and venue for outrageous art and music shows in a former cannonball factory.

Risk arrest while partying to fund art.

A tiny museum housed in a New York freight elevator specializes in the "overlooked, dismissed, or ignored."

Built as a gift to the hottest tastemaker of the time, these hidden quarters remain an Art Deco showpiece.

A treasure trove of artifacts, books, and artwork from the "golden age" of exploration.

A DIY art gallery/music venue/lecture hall dedicated to video game culture.

A band of aerialists and circus performers putting on incredible shows in East Williamsburg.

Tucked in a nondescript downtown Brooklyn mall is a bar containing a remarkable turn of the century anatomical wax collection last seen in 1920s Berlin.

Spike Lee's provocative film is officially honored right where it was made, the first time a work of art was used as a secondary street name.