Hidden on two floors of downtown building, the library has an incredible deal on rent.

Where beautiful signs live on forever.

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

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

The oldest bibliophilia club in America, with exhibitions on historic books and graphic arts.

Detailed facade of a brownstone in Boerum Hill.

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

This preserved wilderness hides the remains of a colonial grain mill used to feed George Washington's troops.

The rare American Civil War-era weapon was never fired in anger.

One Brooklyn man's collection of life-size fiberglass statues has taken over his entire yard.

Piano-making empire filled with 200-year-old steam machines still churning out 1,000 instruments a year.

This landmark building is now a vibrant performing arts space with musical acts from around the world.

This hidden oasis features a stunning view of the Hudson River and the Palisades from a castle-like museum.

Two New York rooftops are home to the largest rooftop soil farms in the world.

One of the largest wooden constructions in Europe was meant to be a casino, but soon became an orphanage.

The highest rapid transit station in the world.

First a horse rendering plant, then a 19th century landfill, this beach is full of glass from thousands upon thousands of broken bottles.

This plot of old-growth forest is the largest surviving remnant of New York City's original woodland.

The highest point on the island known for buildings that touch the sky.

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

A former connection to City Island, it has been abandoned since the 1930s.

Scattered around Atlanta are little doors with big charm.

An underground magnet for ever-changing street art.

Three-story slide through the New Museum.