The two cities bombed with atomic bombs in Japan were Hiroshima and Nagasaki. The first bomb was dropped on Hiroshima on August 6, 1945, and the second on Nagasaki on August 9, 1945. These were the only two cities in Japan attacked with atomic weapons during World War II, and the bombings led to massive destruction and loss of life. Hiroshima was hit first because it was an important military and industrial center, and Nagasaki was struck three days later after the first attack did not end the war immediately. Japan had also been heavily bombed by conventional air raids before those attacks. Tokyo, for example, suffered devastating firebombing in March 1945, but that was not an atomic bombing. If you want the answer in one line: Hiroshima and Nagasaki.
