Monolithic structure among beams, pillars and slabs. The prefabricated pillars, produced in a plant and provided with the right dimensions and the holes for the lodging the beams, are positioned and fixed to the foundations. After that, it is possible to lodge the steel beams, produced in a plant. In order to complete the horizontal supporting structures, it is necessary to place the slabs and pour the concrete: in this way it is possible to obtain a monolithic structure among beams, pillars and