A varnishing plant comprising: a platform on which a plurality of work stations are defined, each of which is adapted to receive a vehicle, a spray booth movable on the platform and positionable on each of said work stations, and an air supply and extraction system associated with the spray booth, wherein said air supply and extraction system comprises a fresh air intake duct and a polluted air exhaust duct, stationary and communicating with an external environment, wherein the polluted air exhaust duct communicates with air suction volumes located below said platform, wherein said fresh air intake duct has a plurality of openings located at respective work stations, and wherein the spray booth comprises a fresh air suction mouth selectively connectable to the opening located at the work station on which the spray booth is located.