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

The final resting place of the poets Shelley and Keats.

Stalactites and stalagmites in a beautifully lit cave.

2300-year-old Roman road connecting the empire.

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

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.

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

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

A gorgeous example of 13th-century Gothic architecture.

These elaborate gothic monuments honor Verona's medieval lords.

A whale rib was used to advertise the store by the arch that offered exotic goods from far away.

Pilgrimage site for star-crossed lovers.

This medieval castle was reconstructed by Carlo Scarpa.

An architectural oddity where the triglyphs of the courtyard of walls create an optical illusion.

A room filled with frescos that make it seem like the walls are crumbling down while giants die in despair.

A medieval tower with a suspended iron cage used as an open-air jail for criminals who were exposed as a warning.

It took more than 300 years to build this church, which is home to two sacred vessels believed to hold the blood of Christ.

The oldest church in Mantua was buried for centuries under the facades of other structures.

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

Architectureal fantasy quarter of Rome.

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

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

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