Ole & Godtfred Kirk Christiansen

Danish carpenter and toymaker Ole Kirk Christiansen and his son Godtfred were designing old-fashioned toys when, in 1947, they came across a product designed by British child psychologist Hilary (Harry) Fisher Page: small plastic blocks with interlocking studded tops and hollow bottoms. The Christiansens, who called their company Lego — a contraction of leg godt (play well in Danish) — started making their own version, which they eventually called Lego Bricks.

The key to Lego's success was the way the bricks fitted together. Early versions were either too hard to take apart or did not lock firmly enough. The Christiansens persevered and in 1958 finally settled on the right formula by adding hollow tubes in the bricks' underside. Lego's popularity rocketed. There were train sets, dollhouses, spacecraft, motorcars and eventually human figures with movable arms and legs.

In the past decade, Lego has struggled as kids spend more time playing video games or surfing the Web. After flirting with more complicated and faddish products, the company has decided to move back to simpler offerings. The beauty of Lego — and the genius of the Christiansens was in recognizing this — has always been that it fuses construction and imagination. There's something wonderful about the fact that, with a few bricks, you can become an architect and piece together a house. Add a few more and you have a tower. Layer by colorful layer. Brick by brick. Final piece. Fun.