http://tinyurl.com/rhkke (New Scientist)
"Alexander wasn't quite so great after all. Sure, he conquered most of the world known to the ancient Greeks, but he didn't found the Egyptian city of Alexandria - he just rebranded it. It now seems that this part of the Nile has been settled for at least 4500 years, pre-dating Alexander's arrival by a good two millennia. Alain Véron from the Paul Cézanne University in Aix-en-Provence, France, and colleagues made the discovery by measuring the variations in lead concentration in a mud core from Alexandria's ancient harbour. They determined how lead levels had changed over time by carbon-dating seashells found in the core. Clear pulses of lead contamination occurred between 2686 and 2181 BC and then again from 1000 to 800 BC."
See the brief summary on the above page for the full story.