The oldest stone house in Paris was built by its most famous alchemist.

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

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

The history of occult science is turned into a creepshow at this lurid Prague tourist attraction.

Italy's third-largest Roman arena gives a peek into the underground operations beneath the ancient spectacles.

A medieval weapon rumored to have been used by the brilliant poet himself.

Caligula's colossal pleasure ships, discovered by Mussolini only to be lost in flames.

A beautifully well-preserved ancient Roman villa.

The Roman Emperor's lost summer home and grotto full of enormous sculptures sit along the Italian seashore.

This historic recreationist school churns out warriors that may very well have had a fighting chance in Rome's pits of the day.

The Emperor Tiberius' palace of debauchery.

Gods clash with machines in a power plant regenerated as a museum.

A gorgeous medieval library where the books are kept in chains.

The "Greatest Sewer" of ancient Rome is one of the oldest sewer systems in the world, and is still in use.

Italian poet Dante Alighieri is entombed in this small mausoleum in Ravenna, and his hometown of Florence has never been too happy about it.

A labyrinth of ancient tunnels hidden below the city holds the ruins of 2,500 years of history.

This hill made entirely of ancient Roman jars was simply a garbage dump to the people of the time.

Rome's ancient Etruscan rival, now a park full of ruins.

This Roman arch marks the location of an ancient gate at one of the Seven Hills of Rome.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

Medieval torture techniques with a modern conscience.

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

Architectural monsters are devouring this palace's every door and window.