Short answers, pulled from the story.
The earliest known dam is the Jawa Dam in Jordan, which was built as early as 3000 BC. This stone and earth barrier stood northeast of the capital Amman and predates the pyramids of Egypt by centuries.
Roman engineers introduced hydraulic mortar and Roman concrete during the Roman era to allow for structures of unprecedented scale and durability. The Romans were the first to build arch dams, where the reaction forces from the abutment stabilize the structure against external hydrostatic pressure.
The Aswan Low Dam in Egypt was completed in 1902. This gravity masonry buttress dam on the Nile River was designed by Sir William Willcocks and involved eminent engineers like Sir Benjamin Baker and Sir John Aird.
In 2008, it was estimated that 40 to 80 million people worldwide have been displaced from their homes as a result of dam construction. This displacement often occurs in the name of the common good and can lead to abuses of the masses by planners.
The Three Gorges Dam on the Yangtze River in China is more than five times the size of the Hoover Dam. This massive structure created a reservoir used for flood control and hydropower generation, requiring the loss of over a million people's homes and their mass relocation.