September 16, 1991. The building of the base of the Tower, the largest undertaking of such a mass pouring of concrete ever done in France. It was first neccessary to build a vast steel armature into the foundation of the base, before starting the fundamental building of the socket on which the Tower will rest. It required 25 hours of constant pouring of concrete which was supplied by 4 large production units at full operation, before the final completion of the platform. During several days the concrete underwent a chemical solidification process at a temperature of 67C in the core, and 30C in the outer layers. One of the reasons for the important internal metal structure was to ensure that in the cooling off process the concrete would not crack or splinter.