César Baldaccini's iconic sculpture of a 40-foot thumb stands tall in La Défense.

This castle-like building in Manhattan helped destigmatize cancer in the 19th century.

This whimsical group of statues is a favorite of children who love to climb all over Lewis Carroll's beloved characters.

Storage warehouse of the rich and famous.

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

Rummage through this sunken ship, but leave your scuba gear at home.

Once home to the country's most gargantuan ships, this graving dock now waits for people to buy furniture.

There are owls with glowing eyes in Herald Square.

An unconventional space for art and science housed in a massive old warehouse.

A semi-scholarly approach to sex.

Built as a home for the Union Porcelain magnate in 1867, now the Greenpoint Reformed Church and home to a ceramic mystery.

The one-time office of the architectural firm that ushered in the Gilded Age is now a Club Monaco.

New York City's only preserved family home from the 19th century.

These historic buildings once housed the headquarters of one of the most infamous gangs of New York.

The artist and New York City icon lived, worked and died in this converted carriage house owned by another iconic artist, Andy Warhol.

Built hundreds of years ago this downtown iron barrier once protected a much despised king.

A clock set into the concrete outside a Manhattan jeweler has been telling time underfoot for over a century.

The oldest Methodist church in the United States has been spreading the good news for over two centuries.

By day this New Orleans square is for pedestrians, but by night it is a kingdom of kittens.

A bronze plaque at an intersection in Hoboken marks the place where the game of baseball first took shape.

A hidden treasure in London with a rich medieval history, and the resting place of many luminaries.

The former home of the reclusive "Weird Wendels" who dominated New York real estate a century before Donald Trump.

A bit of retro transportation flair preserved in the world's largest department store.

The remains of an ancient Roman teenager are memorialized at the base of a modern London landmark.