A museum dedicated to a secret military hospital hidden beneath a castle in Budapest.

Once the home of a hermetic monk, this cave now houses a small church.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

The only museum with its curator—and her pets—buried inside.

100 year tradition of fist fights, marked by marble footsteps.

This community on a small Venetian island has taken to painting their houses in bright neon hues.

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.

Two stone columns flank the grand Venice square, but there were supposed to be three.

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.

Where Venice's gondolas go for a tune-up.

It is still illegal to "quarrel" at this unlikely urban oasis built on top of an electrical substation.

Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

Böttcherstraße's bells, extolling Nordic virtues and the great conquerors of the world.

Hamburgers are intensely proud of their tunnel beneath the river.

Sometimes an island, sometimes a rocky outcropping connected to the world by a tiny suspension bridge.

A fantastic castle rumored to be the birthplace of King Arthur.

It is said the legendary wizard once lived in this sea cave beneath Tintagel Castle.

A disastrous D-Day rehearsal was relatively unknown until this sunken tank was discovered 40 years later.

Take a sea tractor to the Art Deco hotel on the island that inspired Agatha Christie.

This historic Benedictine monastery brews a booze so toxic that it has often been blamed almost singularly for Scottish hooliganism.