A monument to the three wars that led to German unification towers within a Berlin traffic circle.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

The footprint of a frustrated devil in Munich's Cathedral.

Daily jousts and dancing barrel makers in Munich's mechanical clock.

A stairway to heaven, or to nowhere at all.

Go surfing on this urban wave, "hacked" by local surfers.

A unique opportunity to stay the night in retrofitted sections of sewer pipe.

This one has sailed five times as far as Sir Francis Drake's famous ship.

An extraordinary collection of scientific instruments - and Einstein's chalkboard - inside the world's oldest purpose built museum building.

This ornate English estates "Prodigy House" still bears the cannonball marks of civil war.

Mysteriously stacked storefront paths give this medieval British town an iconic style like none other.

The western face was supposedly left clock-less to snub the Welsh.

19th century tunnels burrowed under Liverpool.

The red letters in the literary pavement leading to the library form a mysterious code.

Dating back almost 400 years, the oldest public collection library in the United Kingdom was once the study hall of Karl Marx.

A Victorian Gothic masterpiece housing a world-class collection of rare books and manuscripts.

Be on the lookout for the symbolic insect all over the city.

Have a seat with the father of modern computing at this Manchester monument.

A 400-year-old church covered floor to ceiling in ex-voto offerings from the faithful.

France's national museum of scientific and industrial instruments.

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

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

A series of abstract, silly sculptures represent the works of a great modern classical composer.

Resting in the middle of an Austrian river, this sci-fi "island" lets people cross in neon style.