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

Golden cobblestones remember a time when this small alley was used to avoid having to give a Nazi salute.

This Nazi-built amphitheater was constructed on a sacred mountain site used by various German cults.

No need to strap in for a "ride" on this walkable roller coaster.

These bronze pamphlets remember a remarkable group of Germans who fearlessly opposed the Nazis in the very center of their power.

This "floating railway" is one of the world's oldest monorail systems.

The 1936 Summer Olympics site is a crumbling remnant of sportsmanship and a history its host country would like to forget.

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

Three connected pink triangles memorialize persecuted gays and lesbians throughout history.

A public urinal so pretty, it was declared a national monument.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

The former home of a mad diplomat is said to still be marked in bloody, arcane scrawls.

An Amsterdam street lined with antique shops each one dedicated to a different obscure collection.

A beautifully eclectic mix of architectural styles.

This 22-floor tower's Skydeck offers panoramic views of Amsterdam.

This unattributed sculpture in Amsterdam is hiding in plain sight.

This city square is home to Amsterdam's oldest church and a statue honoring Dutch sex workers.

This lonely waterfront memorial to the men of the Titanic was erected by the "Women of America."

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

The United States Capitol's former columns still stand.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

Descend into the tunnels to experience the life of a coal miner.