Renaissance villa and gardens complete with a tormented colossus.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.

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

An alchemist's "magic door" stands in the middle of a Roman park.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

A 16th-century horror show built in a lovely Italian garden.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

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

An ancient monastery, a locked room, and a mysterious book heist.

Museum in a swimming pool where the water still flows.

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

Ivy-covered Medieval tunnels cut through this charming town in France's Loire Valley.

Sleep in a climate-controlled plastic bubble for the night.

The world's largest reflecting pool is just two centimeters deep.

This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

A mosaic-tiled house built by graveyard sweeper Raymond Isidore.

This stunning French estate was so lavish that it landed its original owner in jail for the rest of his life.

The fantastic architectural models of a French traveler.

A medieval military street hidden beneath a charming French fishing village.

A natural arch carved by a river gave its name to the so-called "Cave of Forgotten Dreams."

Avant garde house of Pierre Cardin on the Cote d’Azur.