Edinburgh's oldest statue hides within a parking lot behind the city's iconic cathedral.

A labyrinthine network of chambers with a storied past hides below Edinburgh's South Bridge.

A roadway designed for a visiting monarch.

Amsterdam's former hotspot for public executions and dissections.

The topiary maze at the Habsburg hunting lodge.

An ornate private entrance to the Vienna subway built specifically for the emperor.

Baroque celebration of the end of the Great Plague of Vienna.

While most wind tunnels test scale models, the "Cave of Winds" was large enough for actual airplanes.

Home to items never before seen by the public.

Look closely and you’ll notice that the color changes a third of the way up the tower.

The monument's pointy aluminum tip has been melted down by repeated lightning strikes.

There’s a hidden military meme engraved on the World War II Memorial.

An overlooked memorial honoring the local Washington residents who died in World War I.

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

Decades before the scandal, this staircase on the river was a literal "water gate."

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

Northern Ireland's Brobdingnagian stepping stones.

This ancient Irish tower could easily have stood in for Rapunzel's prison.

One of Ireland's most infamous prisons for rebels including men, women and children.

This supermarket offers shoppers a window into the past alongside their groceries.

A statue in the center of Dublin dedicated to one of their favorite sons of rock & roll.

An enigmatic monument to the Irish revolutionary who plotted an uprising against British rule.

This courtly monument celebrates an influential comedian who turned taking the piss out of the powers-that-be into an art.

The comedy and tragedy of Oscar Wilde is preserved in a Dublin park, captured in a sculpture of colorful stone.