Mental Floss

DESIGN









A fallout shelter sign left over from the Cold War still visible in Brooklyn, New York.

Tens of thousands of fallout shelter signs, with three yellow triangles in a black circle, are visible on building façades today. They serve as grim reminders of the hottest flashes of the Cold War. So why are they still around?

Tim Brinkhof
The cutest part of any hospital.

Baby viewing windows were once a staple of hospital maternity wards across the country, but now they feel like a relic from a bygone era. Read on to learn about their history—and the real reasons why they vanished.

Lauren Dana








The first soccer balls weren't even made out of rubber.

Dive into the history of soccer balls, including how they evolved from their earliest form, when they were made out of pig bladders, into the hexagon design we see today.

Erik van Rheenen
Frank Lloyd Wright’s masterpiece.

Its cantilevered tiers hang over a 30-foot waterfall—Frank Lloyd Wright’s ingenious way of melding the human-made structure with its natural surroundings. Here are 12 facts about its history and legacy.

Kirstin Fawcett