Perhaps it's worth mentioning some lesser known big achievements of the Manhattan Project. It's not the scientists. It's Hanford and Oak Ridge. Hanford was not only nuclear reactors but a city of more than 43 000 people out of literally nothing. Oak Ridge had the largest building in the world, K-25. It was only surpassed by the Boeing Everett Factory more than twenty years later. These two sites were also the major cost centers of the project. Science is cheap. Enriching uranium and manufacturing plutonium -- especially when no one did it before -- is not.