One of the last free public hot springs is decorated with hippie art.

California's own medieval Italian castle, authentic down to the 300-year-old iron maiden in the dungeon.

This naturally heated mountainous creek has created a group of neon blue pools of potentially deadly boiling water.

This rare example of a "tidefall" is a spectacular drop from the cliffs down onto the beach.

Canyon walls shrouded in ferns.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

A modern-day Lascaux cave underneath Paris.

A museum of carnival attractions where you are invited to ride the rides.

A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

This massive library holds what was once the largest book collection in the world.

Abandoned railway line circling the city of Paris.

A special area of the National Archaeological Museum of Naples is located inside a metro station.

Crammed into several rooms of a Staten Island home, this museum is a vodka-soaked paean to the pleasures of drinking.

Walk through spectacular aisles of hanging meat and wagon wheel–sized cheese at the world's largest wholesale food market.

France's national museum of scientific and industrial instruments.

An ancient necropolis of magnificent tombs.

Once part of an ancient international harbor, it's now an all-you-can-eat shrimp buffet for flamingos and other water birds.

A magical museum of fairy tale treasures near Cyprus' buffer zone.

In Rome’s Jewish ghetto, a 200-year-old bakery still makes the neighborhood’s historic sweets.

These hut foundations are believed to be the residence of Romulus, founder of Rome.

A magnificent waterfall is also home to the remains of a Roman hydraulic engineering system.

Rome's ancient Etruscan rival, now a park full of ruins.

This large, circular tomb is the final resting place of the first emperor of Rome.