One of the smallest bookstores on the planet.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

An ancient and majestic fortress that played an integral role in Portugal's road to independence.

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

The lesser-known Alice sculpture of Central Park dedicated to the “godmother of American children.”

The best way to get a sneak peek at the movies.

An accidentally hidden library containing the ephemeral history of New York.

Once the tallest building in the world and the site of “the highest dinner ever held in New York” this building now holds the most expensive penthouse in the city.

Constructed in the 1920s, this former pencil factory is now an office building.

Ornate "Renaissance Revival" style building.

One of the first major shipyards in Brooklyn.

Known as the "Forgotten City" it was home to industry, riots, artists, squatters, and to one of the largest single disaster fires in New York City.

The home of one of America's most beloved fictional characters has become a real world landmark.

A well-worn marker in a forgotten alleyway is all that remains of what had been one of Manhattan's most beautiful buildings.

Unrepaired walls from a 1920 anarchist bomb attack.

The last remnants of what was once one of the world's grandest hotels can now be found in a Manhattan subway station.

Nondescript elevator doors open to reveal a stunning, surreal world.

Cryptic messages embedded in the New York City sidewalk.

An odd, ancient window that may have once been part of a brutal prison is embedded in the side of New York's Police Plaza.

There’s a secret bunker inside the Brooklyn Bridge, but the city won’t say where.

This humble historic facade hides a history of boozing and the gentlemanly sport of rat-fighting.

Revolutionary War casualties fill the only 17th century structure remaining in Manhattan.