This frog-themed restaurant was frequented by Picasso, Saint-Exupéry, and more.

A grotto-like lodge decorated with gilded mosaics, rocks and a noisy waterfall was the setting for the most sumptuous pleasure house of 1900s Europe.

The subterranean "lake" below the Paris opera house inspired the Phantom of the Opera's lair.

Statue of death tucked in the University of Medicine courtyard.

A museum on the history of Paris, including a set of Napoleon's toiletries, Proust's room, and relics of the Revolution.

The ruins of a Duke's bucolic dream, where camels once roamed alongside "Dutch" windmills and faux-Italian vineyards.

Behind the pink curtain, Au Bonheur du Jour, an art gallery of erotic archives.

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

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

After years of being casually peed on by humans, this tree is peeing back.

A giant snail sculpture looking longingly at the German traffic museum.

Among the ostentatious rococo ornamentation of this church, an image of death cuts the life-thread.

This tribute to the 16th-century composer is now an unusual shrine to Michael Jackson.

The telescope that discovered Neptune.

A serious museum dedicated to two German comedians.

These blingy, baubled skeletons lie in glass boxes inside a baroque Bavarian church.

This small town in Germany was once a center of peppermint production, and has the museum to prove it.

The prototype for all Nazi concentration camps.

This unique abacus hanging in the Technical University of Munich actually tells the time.

King Ludwig I's collection of beautiful women.

A subterranean display of public art and architecture.

On high feast days, the entire blue-glass front of this modern church opens up to reveal the small wooden church inside.

An Orthodox church inside a small "Garden of Eden" built by a man who had a vision.

A stairway to heaven, or to nowhere at all.