Two awe-inspiring globes from the reign of the Sun King hang from the ceiling of France's national library.

A silly medieval mural preserved on the side of a Viennese house.

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

An Art Nouveau building covered in animal gargoyles and grotesques.

Flamboyant architecture from the turn of 20th century.

This half-finished "city of toys" was almost Italy's own Las Vegas.

A collection of grotesques lines the walls of this Italian villa.

David Sedaris called it "The greatest shop in the world."

Over 50 exquisite hand-painted Renaissance maps decorate a Medici storage room.

As can be expected from a centuries old church built in a canal city, the undercroft of this house of worship is beautifully flooded.

A submerged archeological park still holds the wonders of a Roman Sodom.

On rare days, this abandoned castle's gatekeepers open its doors, revealing the eye-popping splendor hidden inside.

This medieval Italian town is a sheer (and beautiful) cliffside defense.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

More sculpture than building, this architecturally significant temple was built on the spot of Saint Peter's crucifixion.

Museum dedicated to literary greats of the Romantic Period is also the home in which Keats met his untimely end.

Sitting on an Italian hilltop is this surreal fortress built by the mad inventor of electrohomeopathy.

Long-abandoned art nouveau baths beneath Milan's Piazza Oberdan.

Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.