This simple Manhattan salt house is artfully shaped... well, like a giant granule of salt.

Amid skyscrapers and traffic exists this unique aquatic ecosystem.

One of the city’s oldest watering holes was originally the home of a famous James Brown (not that one).

In its day this historic fort held 100 cannons pointed in almost every direction to protect New York.

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.

Lie in a hammock where George Washington stood.

The original toys that inspired the beloved children's stories are on display at the New York Public Library.

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

A crumbling hospital from the 1850s on Roosevelt Island.

This futuristic airport terminal was abandoned for decades before reopening as a hotel—with a vintage plane of its own parked out back.

Huge masonic hall in Philadelphia with lavishly themed rooms.

An outdoor urban gallery of large-scale artworks by the world's most influential street artists.

Mural made of 100,000 pieces of hand blown glass, and one of the largest glass murals in the US.

Chicago's Navy Pier on Lake Michigan was a training hub for aircraft carrier pilots during WWII.

These chunky stone towers out in Lake Michigan are the key to Chicago’s drinking water.

Illegal drag racing two stories beneath Chicago’s streets.

This historic hotel invented the chocolate brownie.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

Prolific outsider artist Sid Boyum's concrete sculptures add whimsy to Madison's Schenk-Atwood neighborhood.

The last surviving submarine from a strange chapter of Finnish history.

This atmospheric museum honors a family who hid Jews during the Nazi occupation of Latvia.

Wooden pavers represent a 17th-century barrier that gave Wall Street its name.

One of the most iconic neon ads of former East Germany.

The European Union’s tallest freestanding structure provides radio and television broadcasting to half of Latvia.