Alessi generated three separate stylistic groups of work which correspond to his activities in Perugia, Genoa, and Milan respectively. For each group he exhibited a characteristic reduction of basic architectural units into simple geometric forms. He created designs that depended on a refined coordination of parts within the whole and on the use of distinct structural units. Even when Alessi included dense ornamentation within his buildings, the structural elements remained clearly articulated. He favored the use of paired columns or pilasters set on pedestals. He generally created a rhythm with his facades using alternating window pediments. In later works, Alessi developed a geometric, tapering order enunciated by rounded arches. Allessi's style permeated the residences of the Genoese aristocracy. His ornate decoration revived the Lombard tradition which had been suppressed earlier in the century by Bramante and his followers. Alessi died in 1572.

References
Adolf K Placzek. Macmillan Encyclopedia of Architects. Vol. 1. London: The Free Press, 1982. ISBN 0-02-925000-5. NA40.M25. p62.