This life-size replica of the Statue of Liberty's flame is also a tribute to Princess Diana by default.

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

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

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

19th century pendulum and a clock restored by a rogue group of guerilla artists.

France's national museum of scientific and industrial instruments.

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

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

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

One of the oldest medical collections in Europe focusing on rare surgical instruments.

This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

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

The vast, legendary catacombs hold secrets much stranger than stacked bones.

Leaf through over 30,000 artists' sketchbooks in what may be the world's largest collection of doodles

A curious fountain that has no water and includes Satan, a crab, and 9 giraffes.

The headquarters of a pioneering cast iron and cast aluminum cookware company is in ruins, but still standing.

In this relatively flat state the highest point is an honored place.

These sub-farmland caves are home to a majestic stalactite known as the "Crystal King."

This Vietnamese hell cave lets visitors take a walk through a devilish underworld full of demons.

This coastal cavern is associated with the Hawaiian god of creation.

400 million years of erosion shaped these fascinating seaside caves, which made an appearance on 'Game of Thrones.'

Twin Peaks' real life Double R Diner has been restored to its damn fine television look.

A giant milk bottle from the 1930s beckons drivers to this diner.

This old-fashioned candy shop, ice cream parlor, and diner served as the setting for one of TV's most controversial series finales.