The construction of the Chicago Pile-1 reactor

Beginning in October 1942, and led by Italian physicist Enrico Fermi, members of the Classified Metallurgical Laboratory project worked to build a lattice of graphite and uranium bricks in a 20-foot-high spherical structure known as Chicago Pile-1 - in the hope that it would create a chain reaction that would grow from the splitting of a single uranium nucleus.

On 2 December 1942, after a series of delays, CP-1 achieved a self-sustaining fission chain reaction for the first time and marked the beginning of today's civilian nuclear programmes.