At the end of the 1960s, opening a studio in Milan, he expanded into advertising, creating campaigns for the likes of Giorgio Armani, Laura Biagiotti, Fendi, Gianfranco Ferré, Karl Lagerfield and Ottavio and Rosita Missoni.
[4] He frequented since 1954 the legendary Bar Jamaica, an artists' hangout in the Brera district, from where the major exponents of Italian contemporary art transited,[5] and where he met Ugo Mulas,Mario Dondero and Carlo Bavagnoli, with whom he established a close bond, including a professional one.
He began collaborating with newspapers and magazines such as L'Illustrazione Italiana and Settimo Giorno, documenting the rebirth of Italian cultural life, new forms of pictorial expression, writers, and journalism.
Until 1959 he worked on reportages on cultural and film personalities; he made trips to southern Italy, photographed French colonization in Algeria and anti-nuclear demonstrations in London, architecture in Paris and northern France.
In 1958, the fundamental meeting of his life took place: that with Anna Piaggi, a fashion journalist destined to become one of the creators of the "made in Italy" myth.
In the early 1970s, Castaldi carried out research on the ethnographic origins of men's clothing through a series of photographs that would be published several times in Vogue Uomo.