Italian cave with exceptional acoustics and an unsavory history.

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

Two very green residential towers cleaning the air in one of Europe's most polluted cities.

This bronze boar's snout has been rubbed to a golden sheen by visitors seeking good fortune.

The mountaintop inspiration for Umberto Eco's "The Name of the Rose."

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

Southern Italy's spinning top village.

A lover's walk between hilltop towns, decorated with graffiti love notes.

A stunning bridge that appears as if it's lunging to the shore, and has a legend of a devilish architect.

The bomb-ravaged remains of of a colossal Neptune.

Secret refuge and museum of the Duke of Florence.

Five candy-colored villages on the Italian Riviera.

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

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

Go inside to really appreciate this 500-year-old technological masterpiece.

Over 50 exquisite hand-painted Renaissance maps decorate a Medici storage room.

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

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

The glowing blue Nymphaeum of Emperor Tiberius.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

Quirky castle designed by the American actor best known for portraying Sherlock Holmes on stage.

Tour the world's largest deep-hole dimension granite quarry, where you can view the plant where gravestones are made and roll a ball down the outdoor granite bowling alley.

Holding multiple historical boats and an entire 19th century village, this New England attraction is the largest maritime museum in the world.

With some 500,000 books across five buildings, this bookstore is a reader's paradise.