We report here on the possibility of a local modification of Co/Pt multilayered magnetic films by focused ion beam irradiation. The changes of structural and magnetic properties are experimentally investigated as a function of irradiation fluence. The method is used to form lateral structures with the periods up to 100nm. The magnetic force microscopy accompanied by Hall effect measurements of the structure indicate the formation of magnetic skyrmion lattices in the absence of Dzyaloshinskii-Moriya interaction.