In the front room of the humble McDonald Ranch House, the world's first nuclear device was assembled on 13 July 1945. The device was then taken to Trinity Site, two miles away, where it was placed into a test bomb and detonated at dawn on 16 July 1945. This event signaled the dawn of a new age and forever changed the human experience. Though nuclear technology was born of war, it also came to serve mankind in countless humanitarian forms. The restored ranch house was preserved as it was on that day in 1945 so future generations could see the historic structure where the atom was harnessed in a technological conquest that altered the course of history and underscored America's solemn obligation to use its power to serve all mankind.