This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

Eighty million natural history specimens call this gargantuan museum home.

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

A memorial for a young woman and her ghost, which are claimed to have caused countless deathly shipwrecks.

Tiny castle in the middle of the Rhine made you pay to pass.

This fountain of a little boy that spits on passersby at erratic intervals is a town icon.

Every half hour the eye-rolling clock face sticks out its tongue to mock the good citizens of Koblenz.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

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

A favorite Paris bar for U.S. expats, including Gershwin, Hemingway, and James Bond.

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

This charming cobbled backstreet is the most Instagramable street in Paris, much to the residents' annoyance.

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

The oldest stone house in Paris was built by its most famous alchemist.

A historic London pub with prison cells in the cellar and a "spy room" on the second floor.