Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

This walkway is so narrow it needs its own light to stop pedestrian traffic jams.

Monument to a suicide protesting the Soviet invasion.

The hidden lair of an alchemist rediscovered in a 2002 flood.

The first museum in the world devoted to sexual gadgetry.

The slender brass strip in Prague's Old Town Square was used to tell time from 1652 to 1918.

This doorless 20th-century elevator doesn't stop or slow down.

A Jenga-style cylindrical tower of books that appears to go on forever.

The ritual has been performed uninterrupted for nearly 700 years.

Walk through a restaurant's refrigerator door to reach this hidden bar.

This colorful but controversial ceiling has been likened to a 21st-century Sistine Chapel.

Climb to the top of its spiral spire for spectacular views of Copenhagen.

Looking strangely like Rome's Colosseum, this unfinished tower has dominated the skyline for over 100 years.

Featuring a meatless buffet fit for kings, this family-owned Zurich eatery is considered the oldest vegetarian restaurant in the West.

The commemorative stone column conceals a secret laboratory.

This solo operation offers the world's only whey wines in flavors such as chocolate-orange.

The narrow passages will challenge even the bravest driver.

The highest point in New Jersey is marked by a massive, if simply named, obelisk.

Hundreds of glow-in-the-dark objects light up a museum in a historic zinc mine.

Traveling this mountain pass reveals quaint stone buildings, stunning Irish scenery, and a bridge said to grant wishes.

A labyrinthine network of chambers with a storied past hides below Edinburgh's South Bridge.

The hidden ruins of an old hydroelectric plant reclaimed by nature.

The ruins of a medieval monastery named after a type of tree.

This spooky statue sits outside a famous Prague theater.