Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

Da Vinci's equestrian statue, 500 years in the making.

Milan's duomo is covered in beautiful carving including a curious "dinosaur-like" beast.

Berlin's beloved bear is immortalized at the Museum für Naturkunde.

Metro station with a claim to rock n' roll fame.

Cold war icon and onetime "hole" in the iron curtain.

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

Started as a kitchen garden, now the second largest botanical garden in the world.

The largest free-standing aquarium in the world resides in a hotel lobby in Berlin.

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

A popular shrine where the Blessed Virgin allegedly appeared in 1830, displaying a holy armchair and two incorruptible remains of Lady Saints.

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

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

Site of a classic 19th-century physics experiment to prove the earth is rotating.

A Parisian cemetery where the elite and artistic are interred beneath an eccentric collection of tombs.

France's national museum of scientific and industrial instruments.

The celebrated eyesore created by starry-eyed sweethearts.

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

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

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.

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

A temple to modernity, tucked away amid Barcelona's more well known museums.

Mountain where Jesus was first tempted by the Devil.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.