A favorite Paris bar for U.S. expats, including Gershwin, Hemingway, and James Bond.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

Noirish green neon marks the location of one of the oldest private detective agencies in France.

Executions were once held near this beautiful 18th-century fountain.

Marie Antoinette and Napoleon Bonaparte were fans of this 200-year-old French chocolatier.

The history of radiation is on safe display at the foot of a radiation science laboratory.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

The site where two doves fell in love.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

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

Paris' fabled purveyor of exotic taxidermy and natural history curios.

A mountain of conch shells created by centuries of fishermen.

A hidden tidal pool that transforms into a frothy natural jacuzzi.

A unique botanical garden housed in three giant geodesic domes.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

This historic old movie house was the scene of one of the Blob's most iconic attacks.

Touching mementoes from those who didn't make it back from World War I still hang in one of New York's oldest bars.

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.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

The world's last remaining store of its kind.

A bizarre house filled with an astounding array of collections.

The museum houses one of the world's largest collections of glass paperweights.

This city square is home to Amsterdam's oldest church and a statue honoring Dutch sex workers.