This exemplar of modernist architecture is meant to captivate and inspire students of the Cooper Union.

This small, hidden cove is home to abandoned boats.

An abandoned Gold Coast-era mansion once intended for the exiled ruler of Albania, who never arrived.

The most confusing clock in New York.

These World War I shooting range tunnels are now haunted halls of underground graffiti accessed through the roots of a tree.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

This old cement mine has been used as everything from a mushroom farm to a recording studio.

This abandoned seaside fortress is now simply an imposing ruin being taken back by nature.

A discreet little stairway on St. Nicholas Avenue leads to a quaint and unexpected cobblestone street of 19th century wooden rowhouses.

You can still ride this 100-year-old work of art in Brooklyn's largest public park.

Visit the monolithic tomb of America's most famous general.

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

An artist's cute bronze subway sculptures belie his violent artistic past.

Once America's longest-manned military fort, now an abandoned hulk.

This Wall Street bar was once a hub of revolutionary activity where Washington famously bid farewell to his troops.

The oldest house in Manhattan is now a museum that remembers the home's sordid history of scandals, vice-presidents, and ghosts.

A popular European tradition makes its way to the states on one of America's most famous bridges.

A natural gas leak provides a flickering flame beneath a waterfall.

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

The oldest surviving synagogue in New York City is now a soaring art space.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

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

Wall Street has a new heroine, a bronze statue of a small but fierce girl.

A tunnel once abandoned now thrives with graffiti art as an off-limits makeshift gallery.