The best Genovese basil is said to be grown in Pra',[3] a western neighbourhood of the city of Genoa. The nearby presence of a large steel mill from the 1950s to the 1980s threatened the cultivar, said to be necessary to produce the "real" Genoese pesto. Now the threat is mostly gone with the dismissal of the mill and the conversion of the remaining lines to less polluting productions.[4]