This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

The former home of France's controversial pop maestro is almost completely covered in ever-changing tributes and graffiti.

An overlooked marble is the only surviving in-place 18th century example of the measurement that changed how we define distance.

This modest marker near Notre Dame identifies the very center of Paris.

135 bronze medallions mark a French meridian line which once rivaled the hotshot Greenwich timeline.

This little-known relic crypt holds stolen parts of a Roman Empress.

"In the Dark" Restaurant in Paris offers dinner in complete darkness.

Once the local rulers had gone these enchanting ruins housed common folk in an almost real life fairy tale.

Captain America, Sub-Mariner, and the Human Torch were all born in this art deco Manhattan masterpiece.

This study room in the New York Public Library saw the creation of one of contemporary America's greatest traitors.

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.

This unmarked and unloved Manhattan subway grate created one of the most iconic images in American cinema.

The name of this famed hospital was once a byword for the horrors of medical and psychiatric care.

During the 19th century, you could pay for violence off a prix fixe menu on this Manhattan street.

The oldest operating apothecary in the US has treated everyone from Thomas Edison to Mark Twain.

This impressive Boston holy house is the American mecca for Christian scientists.

A famous songsmith's custom piano, dubbed "High Society," is hidden just out of sight in one of New York's finest hotels.

A strangely angled West Village home is the only monument to an explosion that took the lives of three American revolutionaries.

A Manhattan courthouse hides a small but scathing memorial to Holocaust injustice.

This seemingly unremarkable boulder is said to bear the hoofprint of the devil himself.

Spinning silently in the lobby of an Art Deco masterwork is a massive vintage model of the Earth.

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

A tree that grows parallel to the ground was declared Brooklyn's "crowning curio" by the poet who saved it.

Collapsing castle on the Hudson river was once the storage site of military surplus business.