Alasdair Wilkins in io9:
Hero, or Heron, of Alexandria, on the other hand, had the astonishing bad taste to be born around 10 CE, which made his inventions so far ahead of their time that they could be of little practical use and, in time, were forgotten. If he had been born in, say, 1710, his engineering prowess and incredible creativity might have made him the richest person in the world. As it is, he'll just have to settle for the posthumous reputation of being the greatest inventor in human history. Seriously, unless you invent a warp drive tomorrow, there's no way you're catching up to Hero.
We know precious little about where Hero came from, and it's only in the last century that we actually became certain which century he lived in. The best guess is that he was an ethnic Greek born in Egypt in the early decades of the first century CE, one of the many people whose ancestors had emigrated from Greece after the conquests of Alexander the Great.
Hero probably taught at the Musaeum at Alexandria, an institution founded by the Greek rulers of Egypt – you can see an artist's conception of it above. The Musaeum was unlike anywhere else in the ancient Mediterranean, a gathering place for scholars and the sciences that would remain unique until the rise of universities centuries later.
But still, Hero doesn't really need a lengthy biography to explain why he's important – his inventions and theories do that quite well. His most famous achievement was a primitive steam engine, which was known as the aeolipile. Others before Hero had mentioned aeolipiles, but he was the first to actually describe in any sort of detail how to make one, and it's unclear whether his predecessors had actually been talking about the same device anyway.