The document discusses the Manhattan Project, the US effort during World War II to develop the atomic bomb. It cost $2 billion ($27 billion today) and involved over 40 labs and 200,000 people across New York, Tennessee, California and New Mexico. The bombings of Hiroshima and Nagasaki in August 1945 were the first uses of nuclear weapons in warfare and caused immense destruction through pressure damage, fallout and potential for nuclear winter. The document also provides a hypothetical scenario of a 150 kiloton nuclear bomb detonated in Manhattan to illustrate the potential damage and casualties of a nuclear attack on a major city.