Derelict buildings are all that remain of a complex at the site of one of the worst mining disasters in Montana history.

Costumed elves and mountain bikers co-exist peacefully at this abandoned Christmas-themed adventure park.

This abandoned amusement park was built on a site with a dark history.

During prohibition, corrupt city officials ran drinking dens under the streets of Downtown Los Angeles.

The loneliest island in New York.

Hanging over one of Japan's "hidden valleys," these vine bridges must be remade every three years.

Decades after testing the polio vaccine on unwitting patients, this historic mental hospital sits in ruin.

What was once a trend-setting, phrase-coining icon of architectural splendor is now a rotting, forgotten hulk.

Tucked away amidst some of the most famous addresses in the world is New York's only fraction of a street.

A crumbling hospital from the 1850s on Roosevelt Island.

A long abandoned hospital building on the outskirts of NYC.

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

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

The first "Hall of Fame" in America was designed by legendary Gilded Age architect Stanford White for what was then the NYU uptown campus.

An abandoned horticulture institute gloomily presides over rows of derelict and vine-wrought greenhouses.