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

The water-powered carriages are long gone, but for over a century this funicular railway has been the fastest route to the highest point in Paris.

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

Those who own or stay at this 500-year-old, allegedly cursed house often meet terrible fates.

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.

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

The only museum with its curator—and her pets—buried inside.

Two stone columns flank the grand Venice square, but there were supposed to be three.

An extensive collection of reliquaries containing the bones of saints housed in the largest Catholic church in Venice.

Thousand-year-old Viking runes adorn an ancient Greek lion at the entrance to the Venetian Arsenal.

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

Taking the subway here means doing so over a bridge located in the middle of an estuary.

1513 Turkish world map, full of European state secrets and snarky commentary.

A sixth-century Byzantine cistern hidden below a modern carpet store.

Have tea in a cemetery with a dazzling view of Istanbul.

A marvel of Byzantine engineering under the streets of Istanbul.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

This historic hotel preserves many treasures from its heyday hosting passengers on the Orient Express.

This column celebrates Rome's victory over the Goths, and may be the oldest Roman monument in Istanbul.

This half-forgotten fortress was constructed by the Ottoman conqueror of Constantinople.

A gorgeous, Gaudí-esque stairway constructed in the city of Istanbul by a prominent Jewish family.

A small etching on the white marble parapet was written in runic script by a Viking mercenary.

Thousands of pieces of art have been carved into the rock at the site of an ancient volcanic eruption.

A burnt-out motel with priceless Native American artwork in the basement, redeveloped into apartments.