In the 11th century Ibn Al-Haytham (Al-Hazem) was called from Iraq to Egypt by the Caliph to engineer the first Aswan Damn. Ibn Al-Haytham's field work convinced him that attempting to build the dam would be a disaster and rather than face the wrath of the Caliph, he feigned madness and went to jail.
It wasn't until the British occupation of Egypt, over eight centuries later, that the first dam across the Nile was successfully built (1898-1902). At the time of the Old Aswan Dam's construction, nothing of that scale had ever been attempted. It was the largest masonry dam in the world.
The British design allowed ships to pass upstream, before overland transport was necessary. After Egypt obtained independence from the United Kingdom, the new High Dam was constructed. It took ten years for it to be built and was completed in 1970. The Old Dam now provides control of tail water for the High Dam. It also supports two hydroelectric power plants, the Aswan I and II.