Finale of "William Tell Overture" can be heard as drivers pass over grooves in the road.

Man-made cave with enigmatic carvings, some say made by the Knights Templar themselves.

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

This 1920s Dutch barge is now a floating bookstore.

This overlooked street light once served as a KGB dead letter box.

Drink your espresso at a Victorian-era urinal in this underground-restroom-turned-coffee-bar.

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

Cat art as far as the eye can see.

Legend says these rocks used to be hunting dogs, a story that may have inspired Sherlock Holmes' most famous case.

This tangled English forest looks like something right out of a fairytale.

Also known as "Robin Hood's tree," this tree became a famed location along Hadrian's Wall before it was cut down in an act of vandalism.

Drink wine handed out through a window as part of an age-old tradition.

A modern sliver of architecture in Roma.

A breathtaking 19th-century trail overlooks Lake Tahoe.

This geothermal hot spring hides beneath a slowly growing mineral dome.

This massive metal sculpture in the shape of a folded paper airplane overlooks a Utah mountain.

Now overgrown, these anti-tank barriers from World War II are sometimes called "dragon's teeth."

An ordinary lamppost situated in the middle of Cambridge has an unusual moniker and history.

This 15-story mural celebrates the 50th anniversary of the musician's iconic "At Folsom Prison" album.