The world's only official college program focused on "clown therapy."

This unique sculpture is often overlooked by pedestrians.

Small Easter eggs are hidden in the ventilation holes of the city's newest trains.

This giant crucifix is like U2's Joshua Tree for Swedish death metal fans.

Stockholm's tiniest statue is of a small boy looking at the Moon.

Now a hotel, this former bank was the site of a robbery that spawned a psychological phenomenon.

A faded sign from the 1920s remembers Baltimore's resistance toward banning alcohol.

The man who first patented the Ouija board rests in peace beneath a headstone that playfully reflects that achievement.

This eclectic, mosaic-clad home includes a bamboo ping-pong loft and a "Whispermaphones" intercom.

One part antique store, one part curiosities hodge-podge.

One of Philadelphia's largest murals resides hidden under this bridge.

South Philadelphia is home to Keith Haring's only surviving in situ collaborative public mural.

A tiny, unmarked beer and whiskey bar above an Ethiopian restaurant in West Philly fails to conceal live bluegrass.

Ant sculptures march up the side of what used to be an iconic spot in punk rock lore.

One artist's love letter to his city and its citizens plays out across dozens of bright murals painted on the sides of decrepit buildings.

Since the 1700s, this old barrel has acted as a post box that relies on the kindness of travelers.

An existential riddle in the world's largest ancient castle.

The risqué mixed-media sculptures are supposedly a metaphor for Czech politics.

More than 500 unique and specially designed cases collected by D.C.'s "Harmonica Case Man."