Once a prosperous mining village, this tiny Taiwanese town is now overrun with cute cats.

The Emperor Tiberius' palace of debauchery.

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

Renaissance hospital featuring a rotating door into which unwanted babies were dropped.

These medieval skyscrapers dominate the skyline of this small Tuscan town.

Erotic art covers the walls of the largest ancient pleasure palace.

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

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

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

This private skyway is filled with art and was expanded explicitly so that Hitler could appreciate a river.

This picturesque Umbrian city has a subterranean side that has long remained hidden.

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

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

Pilgrimage site for star-crossed lovers.

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

The once forbidden "secret cabinet" of erotic art from excavations of Pompeii and Herculaneum.

2300-year-old Roman road connecting the empire.

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

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

The underground sanctuary of a mysterious ancient cult.

The yawning maw of this pagan visage is said to bite off the hands of liars.

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

Lost subway station nestled beneath Toronto's busy commuter line.