Nikola Tesla's former home contains an homage hidden from plain sight.

A three-story copper skybridge connects two Manhattan buildings with Art Deco luxury.

Read a book next to a Midtown waterfall.

A miniature rainforest is growing inside of a Midtown Manhattan office building.

Try not to get slimed in Tribeca.

Manhattan’s Battery Park has a whimsical carousel full of spinning, glowing fish.

Dodge prohibitionists and slide through the telephone booth in Crif Dogs.

The "Seinfeld" diner.

This lower Manhattan bar is set up in an old bank vault that rests beneath a skyscraper that hides even more historic splendor.

Hear the tales of New York's most notorious criminals.

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

Under a glass sidewalk lie the remains of some of Manhattan's oldest buildings.

Amid the bustle and noise of the Financial District hides a secluded garden oasis above the city streets.

Architectureal fantasy quarter of Rome.

The smaller of the three towers of San Marino is a former prison inaccessible from the ground level.

One Italian taxi driver covered his entire house in small seashells creating a weird bit of architecture that is preserved to this day.

Drink wine handed out through a window as part of an age-old tradition.

This private skyway is filled with art and was expanded explicitly so that Hitler could appreciate a river.

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

The only remaining arch of the oldest stone bridge in Rome stands in the middle of the Tiber.

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

A forgotten "city of water" underneath the famous Trevi district.

This historic recreationist school churns out warriors that may very well have had a fighting chance in Rome's pits of the day.

A huge enchanting public park just outside the ancient walls of Rome.