A medieval military street hidden beneath a charming French fishing village.

An Orthodox church built by the Royal Family for the Russian community exiled to the French Riviera.

A memorial to honor those who were killed in a Bastille Day terror attack in Nice.

The first green space constructed on an elevated viaduct.

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

A pink sandstone column once used in ancient times to measure one's belly after a night of debauchery.

Visitors dating back to the 1600s carved their marks in the stones of the iconic tower.

There has been an astronomical clock on this spot since the 14th century.

St. Mary's features one of the most spectacularly decorated cathedral interiors in all of Europe.

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

A Trabant car, a kangaroo statue, and a plethora of plants take over this abandoned-factory-turned-bar.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

The 2,000-year-old beam is tucked within the pedestrian entrance to the old London Bridge.

Where condemned pirates met their grisly end at the gallows on the River Thames.

Scattered throughout London are ancient remnants of the city's former bounding wall.

This hidden green space is the city's second largest conservatory.

A hands-off space for graffiti artists to hone and display their skills.

Eighty million natural history specimens call this gargantuan museum home.

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

A colorful street named for the legendary Australian rock band.

It's said to be one of the most significant collections of contemporary Chinese art in the world.