An incredible mosaic-lined monument said to have held the remains of an ancient Roman empress.

A mysterious shape catches the eye in this 16th-century painting.

A wonderfully eclectic Victorian aquarium lies in the basement of the Horniman Museum.

Thousand-year-old Viking runes adorn an ancient Greek lion at the entrance to the Venetian Arsenal.

This Roman statue is missing a limb from when the Venetians stole it from Constantinople during the Crusades.

This impressive working clock made of 16,000 plants changes its flowers twice a year.

The "Little Ones," show Portugal in full miniature splendor.

Outstanding taxidermy dioramas showcase the grandeur of the continent's wildlife with spooky realism.

This poignant art installation raises awareness of violence against women.

This 11th-century castle sits so low you can't see it behind the surrounding buildings.

A beautiful Victorian statue shows France's enduring love of the rhinoceros.

A labyrinth hides in plain sight at each of the city's 270 Tube stations.

A cone-shaped top and cylindrical body set this 900-year-old structure apart from other Italian bell towers.

Old ships and machinery fill a historic harbor in the city that's home to Europe's largest port.

A nearly 25-foot concrete sculpture of Sylvette, Picasso's muse.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

The library houses an incredible collection of some of the world's most impressive books and manuscripts.

A little slice of Japan and its aesthetics in London's Holland Park.

This museum inside a museum tells the story of London's timepieces.

One of the world's oldest working clocks is curiously missing the Zodiac sign of Libra.

With a history of slaughter, feast, and famine, remnants of the pork industry decorate this area--even its church.

The former home of France's controversial pop maestro is almost completely covered in ever-changing tributes and graffiti.

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

A French artist's vague warning hangs over Belleville.