Tables of secondhand books fill the inner courtyard of this 17th-century stock exchange.

This unusual piece of Renaissance art depicting the bodily horror of crucifixion and skin disease may have been inspired by fungus-induced hallucinations.

This remarkable checkered church on a Corsican hilltop is fabled to have been built by angels.

France's highest manned weather station is the only one still inhabited by meteorologists.

Sky ships, planes, and portraits left as unique tokens of hope and thankfulness.

The eclectic observatory castle of a 19th-century astronomer and explorer.

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

This church sits upon a peaceful hill and a long, turbulent history.

A 16th-century fountain marks the site of a lost medieval cemetery once filled with mass graves.

A colossal sculptural lion built by the same man who designed the Statue of Liberty.

A series of abstract, silly sculptures represent the works of a great modern classical composer.

In this Parisian garden's grotesque former life as a zoo it fed exotic animals to the bourgeois and put humans on exhibit.

There has been an astronomical clock on this spot since the 14th century.

Hundreds of prehistoric stones, arranged in perfect lines in a French field.

This French castle is said to have once held the Holy Grail but is now a gorgeous mountaintop ruin.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

Known as the "Dodo Manège," this carousel features a herd of animals that have disappeared—or may be gone soon.

A haunting collection of the vanished and disappearing natural world.

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

On any given day this sprawling market houses literally tons of government-regulated gold, gems, and precious metals.

The oldest surviving mosque in the UAE has mysterious origins and unusual architecture.

One of the largest sand dunes in the world is nicknamed the "Scary Mountain" due to its steep slope and sharp incline.

Now harmless, this looming post struck fear into the heart of medieval troublemakers.

This Croatian fairytale castle is slowly falling apart thanks to years of neglect.