In this paper we propose to show some sun photometry results obtained by the MILANO 93 experiment of the AMA (Aree Metropolitane ed Ambiente) Strategic Project of the Italian National Research Council (CNR). The experiment was carried out between the 8th and the 20th of February 1993. The aerosol optical thickness is compared with similar results obtained at Modena (a town in the Po Valley); the meteorological situation is also considered. The measurements were taken at seven different locations across the metropolitan area of Milan, beginning at the Monza racetrack, about 20 km North of Milan, and finishing at Lacchiarella, a rural village about 20 km South of Milan.