A 1,215-foot tunnel transports pedestrians beneath the River Thames.

The curios of pharmacist and collector Henry Wellcome.

An unusual round church in London with a Templar past.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

A 300-year-old tea shop that brought tea to the English people, not to mention the Queen herself.

This probably wasn't what Mao had in mind.

The most famous location in China was home to whole dynasties worth of imperial rulers.

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.

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

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.

This amazingly preserved Doric temple was abandoned before it was ever completed.

The spot where the fascist dictator made some of his most famous speeches including declaring war on Britain and France.

This 6th-century church has the largest and best-preserved collection of Byzantine mosaics outside Constantinople.

Brass cobblestones mark the places where individual Holocaust victims were taken from their homes.

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

A sculpture serving as an homage to Pope John Paul II.

This Italian stadium makes liberal use of fascist statuary to evoke classical sporting arenas.

The 1,000-year-old abbey is the birthplace of modern musical notation.

A sinister pyramid in the Frari contains the heart of the famous neoclassical sculptor.

The mark of the Devil's horns on a marble column in Milan.