The hidden lair of an alchemist rediscovered in a 2002 flood.

Macabre astrological automaton clock dating to the late 1400s.

Two stunning 17th-century libraries and a cabinet of curiosities.

Constructed in the 1920s, this former pencil factory is now an office building.

The largest crypt ever constructed in France was built in the 11th century on an ancient Druid sacred site.

The famous winding walk at Chartres is surrounded in mystery and myth.

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the 20th century.

Unscathed for almost 2,000 years, the best preserved Roman triumphal arch is in a small southern Italian city.

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

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.

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

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.

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

France's most famous cemetery, with some of its most curious tombs.

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

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

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.

The martyr's wax-enhanced skeletal remains lie preserved in a glass case in the Santa Maria della Vittoria in Rome.

Pilgrimage site for star-crossed lovers.

A collection of objects supposedly singed by the hands of souls in purgatory.

Thousands of well-dressed mummies below a monastery.

The oldest operating pharmacy in the world features 800-year-old recipes.

The world's most active stratovolcano is almost always erupting.