This is the oldest Roman-made bridge in the city still existing in its original state.

A complex, nine-layer maze on the grounds of a Venetian doge's playground.

This abandoned Brutalist treehouse is a hidden architectural relic.

This mosaic-lined medieval church was built by the world's first admiral and still holds mass in ancient Greek.

This medieval Italian town is a sheer (and beautiful) cliffside defense.

Crossing this suspension bridge feels like walking through the sky, a fitting tribute to the head of the Apollo program.

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

The Sighignola summit on the Swiss border offers views so breathtaking it's been named one of the most beautiful places in Italy.

An Italian ghost town that fought obscurity, until a mysterious illness brought it to its knees.

This Tuscan lake hides a 13th century town that is still visible when the water recedes.

This curious, round temple is the oldest still-standing marble building in Rome.

The best preserved Paleochristian basilica in Rome hides a number of oddities and secrets.

The graveyard is filled with beautiful funerary art and boasts breathtaking views of Florence.

Natural cathedral designed by Italian artist Giuliano Mauri.

Eco-village hidden in the foothills of the Alps that created a massive system of psychedelic underground temples.

This immaculate and historic water garden culminates in a massive stone dining table with an inset fountain for chilling the wine of the Cardinal's guests.

An underground paleo-Christian burial site composed of the remains of several cemeteries and Basilicas.

A fairytale island floats in the middle of Italy's little-known Lake Orta.

Filled with goldfish swimming in a shallow pool of sea water, this ancient crypt is more wishing well than burial site.

This ancient market is often referred to as the oldest shopping mall in the world.

The secret medieval communication system will whisk your words above the noise of the crowd.

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

Secret refuge and museum of the Duke of Florence.

Abandoned medieval hill town.