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

Located in the thermoelectric factory that once powered the entire city, this Portuguese museum is shockingly fascinating.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

The world's oldest bookshop still in operation.

The attic of a four-century-old canal house hides a clandestine church.

Beneath the city of Lourdes, France is a massive, concrete church.

This bridge was constructed from the rubble of the infamous Bastille.

Historic medieval fortified city in southwest France.

An icy lake tucked among jaw-dropping alpine panoramas.

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.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

This former “ante-chamber to the guillotine” has been refurbished to illustrate the brutal history of French justice.

A museum on the history of Paris, including a set of Napoleon's toiletries, Proust's room, and relics of the Revolution.

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

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

A botanically themed auditorium blooms within the world’s last operating double-decker theater.

A 98-room castle in the middle of Toronto that bankrupted a 19th century electricity multimillionaire.

The most visited, and possibly most controversial, museum in Germany.

The facade of this relic from the Klondike gold rush is decorated with over 8,800 pieces of driftwood.

This Roman statue is missing a limb from when the Venetians stole it from Constantinople during the Crusades.

Where Venice's gondolas go for a tune-up.

The marble facade hides a little-known medical museum with early surgical instruments and rare copies of canonical texts.

Color-coded signs direct drivers on a network of routes designed to avoid Pittsburgh traffic.