Tens of thousands of Africans rescued from slave ships passed through this gate before being settled in Sierra Leone.

It's believed that the dead were once taken out of houses through these now walled-up doors.

Third time's a charm, or in this case, two testicles are.

Depending on how it is measured, this lighthouse can claim to be the tallest in Europe and the tallest conventional lighthouse in the world.

Look up from the busy streets to discover how time is kept!

This skewed English house has looked like it's going to fall over for centuries.

A defensive structure built during the Hundred Years War has remained useful in one way or another for nearly 700 years.

One of England's most famous churches hides a pair of little known architectural treasures.

An impressive armored bronze effigy marks the tomb of one of the medieval era's greatest warriors.

A set of medieval stained-glass windows tell the gruesome story of a Viking siege.

Inspired by Thomas Stothard's painting of the "Journey to Canterbury," albeit with Canterbury natives.

A wonderfully eccentric Victorian-era museum and library.

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

These official units of measurement—including chains and perches—lie hidden beneath tourists' feet in a popular London hub.

Originally meant to hold a statue of King William IV, this support sat empty for years. Today, it hosts a rotating cast of public artwork.

A quartet of tiled art pieces adorn the floors of this prestigious art museum.

This pub boasts a curious history and may have inspired a Dickens character.

Catacombs turned marketplace.

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

After nearly 60 years, there's still a bear at Paddington Station looking for help.

An architectural oddity hides in plain sight on this iconic London bridge.

A memorial for public executions that dates back to the 14th century.

Preserved behind glass, the ruins of a medieval building used to store human remains.

Spitalfields' regal market goat is said to be a monument to the area's migrant population but most are pretty sure it's just a goat.