A 16th-century fountain marks the site of a lost medieval cemetery once filled with mass graves.

This bridge was constructed from the rubble of the infamous Bastille.

The spiral staircase hidden inside this giant Parisian column was likely built for Catherine de Medici's astrologer.

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This little-known relic crypt holds stolen parts of a Roman Empress.

Remains of Roman amphitheater hidden in a sleepy quarter of Paris.

This life-size replica of the Statue of Liberty's flame is also a tribute to Princess Diana by default.

Natural history museum celebrating biodiversity with a parade of taxidermy animals.

In the best of all possible worlds, everyone will get a chance to see this statue in which Voltaire's heart is interred.

The ruins of a Duke's bucolic dream, where camels once roamed alongside "Dutch" windmills and faux-Italian vineyards.

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

Indents in the pavement are all that remain from a grisly death machine in Paris.

The very center of Paris is surrounded by a bevy of strange good luck rituals.

Paris' linguistic guide to the international language of, yes, love.

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

Notorious artist squat renovated into legal studios.

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

This cemetery features modernist statues as strange as its name.

Possibly the oldest church in Barcelona, this basilica has its pagan and Christian mythologies all mixed up.

The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

The 2,000-year-old Roman columns are hidden within Barcelona's Gothic Quarter.

Saint Joseph was said to heal the deaf and blind, but it was a much smaller miracle that got him canonized.

An unusual stroll through gentlemen's erotica demonstrates that pornography is timeless.

The vast, legendary catacombs hold secrets much stranger than stacked bones.