The application, filed in Denmark, described a hollow brick with cylindrical studs on the underside that gripped tightly enough to stack securely yet release easily by hand—solving durability and versatility problems that had plagued earlier plastic building blocks. The design became the foundation of one of the best-selling toy lines in history.
Ole Kirk Christiansen had been making wooden toys since the 1930s in the small Danish town of Billund, but it was his son Godtfred who pushed the company toward plastic and toward solving a problem that had nagged at customers for years: the existing snap-together bricks didn't snap together very well. They fell apart, or they wouldn't come apart at all.
The solution, patented on this day, was deceptively simple—hollow tubes on the underside of each brick that gripped the studs of the brick below with just the right amount of friction. Godtfred and his engineers had tested and refined the 'clutch power' obsessively, and the patent effectively locked in a geometry that Lego bricks manufactured today, more than six decades later, still share and remain fully compatible with.
The company's name came from the Danish phrase 'leg godt,' meaning 'play well.' By the 21st century, Lego had become one of the most valuable brands in the world, and by some estimates, if you divided the number of Lego bricks ever produced among the world's population, every person on Earth would have dozens.
Key people: Ole Kirk Christiansen, Godtfred Kirk Christiansen