Pompeii's less famous neighbor is still revealing her secrets.

Its interior is adorned with some of the best examples of early Christian mosaics.

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

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

This small, ancient Roman temple was once a church dedicated to the patron saint of penitents.

The only remaining arch of the oldest stone bridge in Rome stands in the middle of the Tiber.

A small cell adjacent to this church was once the bedroom for a renowned saint.

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

This cuddly-looking statue symbolizes the bond between Spain and China.

The magic of Spanish aviation housed under one roof.

A masterpiece of Gothic-Mudejar design in Ciudad Real.

With a history of slaughter, feast, and famine, remnants of the pork industry decorate this area--even its church.

A 16th-century fountain marks the site of a lost medieval cemetery once filled with mass graves.

The celebrated eyesore created by starry-eyed sweethearts.

In the "Danish Capital of America," a replica of one of Copenhagen's most iconic buildings.

California's oldest wind harp represents a historic piece of America's Danish history.

Central America's deepest lake is actually a volcanic caldera, surrounded by three volcanoes.

Gustave Eiffel's masterpiece until the Eiffel Tower was built.

One of the most beautiful bookstores in the world hides a neo-Gothic interior behind an art nouveau facade.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

A unique seaside cave where Aleister Crowley faked his own death.

Meant to resemble a massive tree, the building is the best example of Spanish organicist architecture in Madrid.

Part of the wall is preserved in the aptly named Parque de Berlín in Madrid.