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.

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

This former Baroque palace on the historic Calle Montcada is a rare architectural gem and was once the meeting place of an aristocratic scholarly society.

Turntable anonymously received orphans, alms, and groceries.

Week-long block party becomes a competition for the best decorated street.

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

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

The Liverpool street made famous by the Beatles is real.

The quiet field that inspired one of the most famous songs of all time.

19th century tunnels burrowed under Liverpool.

An eccentric 18th century naval officer built a ship's quarterdeck on his roof, the inspiration for Mary Poppins's "Admiral Boom."

The first tunnel to be dug beneath a river, repurposed as an art and museum space.

A hidden treasure in London with a rich medieval history, and the resting place of many luminaries.

A glorious pub known for a spiteful printing feud and its famous typeface lost—then found—at the bottom of the Thames.

Mary Kelly was last seen here before she was murdered by Jack the Ripper.

Giant, friendly pelicans in Central London, the most unlikely of places.

A clock designed to run with perfect accuracy for 10,000 years.

Eighty million natural history specimens call this gargantuan museum home.

Dictionary Johnson’s favorite feline.

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

This legendary stone is of unknown origin, and throughout history has been a literal touchstone for British leaders.

The final resting place to 300 Victorian-era pets hides inside the city park.