An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

This Parisian café sticks almost exclusively to an ethos of reuse.

An oft-overlooked, magically musical monolith that stands majestically between Arlington Cemetery and the Iwo Jima Memorial.

An aptly-named street near the birthplace of the modern LGBT rights movement.

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

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

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

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

First founded in 1472, this is the oldest bank in the world. Its history may explain why we call financial institutions "banks."

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

This shining multicolored metro station deep under Naples is said to be the most beautiful in Europe.

Also known as the Square Colosseum, this building is a prime example of fascist-era rationalist architecture.

This beautiful park on the outskirts of Rome protects the ruins of two colossal ancient aqueducts.

Brass cobblestones mark the places where individual Holocaust victims were taken from their homes.

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

The remains of this 2nd-century Roman temple are incorporated into a modern building.

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

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

The once forbidden "secret cabinet" of erotic art from excavations of Pompeii and Herculaneum.

Where the lovelorn find a home for their sentimental keepsakes.

An eclectic art form practiced by untrained masters is celebrated at this museum in the heart of Zagreb's old Upper Town.

The site where Poe “in great distress, and ... in need of immediate assistance” likely died.

The trials and tribulations of marking Poe’s grave.