Abstract This paper focuses on the characteristics of alteration of the Pietra di Finale, a stone with long tradition in Ligurian regional architecture. The Pietra di Finale is quarried near Finale Ligure in western Liguria, and widely used in the ancient buildings (e.g. by the architect Galeazzo Alessi). Three main types are exploited: white, pale pink and dark pink, and all were the object of the present study. The stone was exposed to atmospheric agents, to investigate weathering processes and eventual suitable protection against the Ligurian climate. In particular we studied a laboratory procedure of ageing by exposing the stone to an artificial acid rain whose composition is the same as the most polluted rains fallen on Ligurian region. Consequently we observed the alterations that occurred on stone after exposure to the same amount of artificial and natural rains. The same procedure was applied to samples protected by a fluorinated copolymer such as Akeogard LTX (Syremont, Italy).