A small plaque highlights the damage caused by German air raids during World War II.

A library where thousands of books explain how to avoid another Great Recession.

Constructed on the ruins of a convent, this tower saved countless lives.

Small museum dedicated to the founder of electromagnetic theory.

This 18th-century fort surrounded by a moat was used to store gun powder and ammunition, and now sits in the middle of a large part in Dublin.

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

Designed by the architect who also had a hand in crafting the Westminster Abbey and Bristol Cathedral.

A majestic lion statue guards this Parisian botanical garden, and feeds on an unsettling item.

The first green space constructed on an elevated viaduct.

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

A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

France's national museum of scientific and industrial instruments.

A mechanized clock where a man fights off a dragon, crab, and rooster.

Egyptian Revival movie palace abandoned for decades and restored in 2013.

What looks like a normal building is really a hollow facade hiding a subway vent.

This museum tucked below a charming cafe gives a brief snapshot of photographic history.

Heralded as the oldest statue in London.

A bronze bust commemorates the heroism of the secret agents who led covert operations against the Nazis.

This peeling mural of Adam and Eve was inspired by the greenhouses at Kew Gardens.

The 700-year-old fortress was the site of Count Orlok's castle in "Nosferatu."

The blood-soaked ruins of the castle where the murderous Blood Countess was walled in alive.

Small sculpted heads of prominent phrenologists mark the outside of their former headquarters.

The long-lost final resting place of an accused witch.

The oldest alley in San Francisco is paved with a reminder of the city's original shoreline.