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

This off-limits room in the National Library of France is home to a system of pneumatic tubes, once used to bring books to readers.

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.

The celebrated eyesore created by starry-eyed sweethearts.

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.

An overlooked marble is the only surviving in-place 18th century example of the measurement that changed how we define distance.

The world's oldest bookshop still in operation.

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

Within the Dadès Gorge, amazing vistas and towering cliff faces can be seen at each new curve and bend in the road.

God's Saharan sandbox of wrath.

A fortified city, home to a remaining population of five families

World's largest film studio, where visitors tour the decaying sets that litter the harsh desert environment.

One of the most spectacular canyons in the world.

This vast masterpiece of Moroccan architecture spreads across 20 acres.

Fortune tellers, snake charmers, poets, and storytellers all gather on this historic square in Morocco.

An awe-inspiring mosque in Morocco with one of the tallest minarets in the world.