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

A vast overgrown cemetery, once known as one of London's "Magnificent Seven."

The curios of pharmacist and collector Henry Wellcome.

An unusual round church in London with a Templar past.

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

The mysterious, fantastical woodland inspiration for "The Lord of the Rings."

At this small museum, visitors can view artifacts from the only battlefield in London during the War of the Roses.

A mineral spring that became all the rage in 17th-century England.

A man's head is enshrined beneath a statue near the first building constructed for the modern Olympic Games.

This muddy wooded valley and the ancient structures it hides are said to be the favored haunt of the legendary Friar Tuck.

This 19th-century island fort built to protect against an invasion by sea.

Walk inside a half mile long crevice right outside the town of Garmisch Partenkirchen.

The busy transport hub is home to the tallest airport slide in the world.

The oldest standing Byzantine church in Athens is tucked within a monastery in the middle of an upscale shopping district.

A statue representing a lost Roman profession that was vandalized for centuries.

This small Spanish village is home to dozens of public paintings meant to trick the eye.

The excellent Swiss museum of witchcraft is led by a modern witch.

This charming, narrow-gauge railway in the Thames Estuary is sometimes referred to as the "Train to Nowhere."

A trove of ridiculously valuable prints and manuscripts under one roof.

A deep mark on the remains of a Roman temple, believed to be left by a legendary warrior.

An atmospheric, medieval-themed book store hides in a 13th-century underground space.

A Byzantine-era church hidden in a wooded area below the Acropolis.

This unusually shaped fortress houses a blend of centuries-old frescoes and modern art.

These legendary stone steps were once used to haul coffins up the rockface.