According to Wikipedia, the wheel was invented around 3,500 BC in Mesopotamia. The wheel is probably the most important mechanical invention of all time. We tend to take lots of essential things in our daily lives for granted: electricity, the alphabet, fire, sewing machines, and so on. And the wheel, as Maximilian Schmid has shared, is certainly one of them. Just look around. The wheel is everywhere: on cars, trains, airplanes, washing machines, refrigerators, clocks, door knobs, faucets, etc. Pretty much all mechanical objects contain some form of a wheel and axle. I'm personally most grateful for this invention when I ride my bicycle. Because bicycling is one of my favorite things on Earth and I find it almost a miracle the fact that this thing can stand on two wheels and can move so fast. One interesting fact about the wheel I found during my research is that the great Inca, Aztec and Maya civilizations, who reached an extreme high level of development, never used the wheel.