This is the entrance to the National Atomic Museum on the grounds of Kirtland Air Force Base, which is adjacent to Albuquerque (NM). It contains historical displays, replicas of atomic weapons, a gift shop and educational facilities.
There are several Web sites that discuss atomic weapons, and their specific use in war against Japan. Visit these sites for different persepctives on the events surrouding their use.
Trinity Site info, location of first atomic test
History & Ethics behind the the Manhattan Project
American Airpower Heritage Museum, Texas
Fifty Years from Trinity, Seattle Times feature