Archaeologists have known for some time that Alexander used the debris of the abandoned mainland city to build a causeway 3,000 yards long and up to 180 yards across. Once within reach of the city walls, he used siege engines to batter and finally breach the fortifications.
But building a causeway in deep water would have meant raising the level of the sea floor considerably - an impossible feat in such a short space of time. However, researchers in France who analysed the coastal sediment record for the past 10,000 years have discovered how Alexander's engineers exploited a natural underwater "sandbridge".
The ''sandbridges'' are formed when sediment is deposited rapidly at a spot behind an island.
I'm still not sure how it worked.