The photographic heritage is composed of  around 1.300.000 original photograps, datable between 1840 and today, representing all the experimental photographic techniques attempted in the nineteenth and twentieth  centuries,  and the work of the most important photographers.  Among them are Nadar, Adolphe Braun, Franz Hanfstaengl, Brogi and Alinari of Florence, Anderson of Rome, Carlo Naya of Venice, Alfred Noack, Giorgio Sommer, Eugène Sévaistre, Stefano Lecchi, the Milanese Alessandro Duroni, Pompeo Pozzi, Luigi Sacchi, Giulio Rossi, Icilio Calzolari, Guigoni & Bossi, Studio Ganzini, Leone Ricci, Varischi & Artico, Giuseppe Beltrami, Luca Comerio, Italo Pacchioni; Abdullah Frères, Bonfils, Antonio and Felice Beato, James Robertson, Fratelli Bisson, Edouard Denis Baldus, Henry Peach Robinson. For the  twentieth century , we see Emilio Sommariva, Antonio Paoletti, Mario Perotti, Mario Crimella, Dino Zani, Attilio Badodi, Elio Luxardo, Bruno Stefani, Giulio Galimberti, Leopoldo Metlicovitz, Claudio Emmer, Paolo Monti, Carla Cerati, Henri Cartier-Bresson, Gianni Berengo Gardin, Lamberto Vitali, Francesco Radino, Mario Cresci, Roberto Crippa, Ugo Zovetti, Luigi Bussolati, Giampietro Agostini, Tancredi Mangano, Francesco Giusti, Cesare Colombo, Aldo Ballo and Marirosa Toscani Ballo.

The Institute houses photographic funds documenting the history of artistic heritage, urban and social history, portraiture, reportage (including Stefano Lecchi's valuable series on the Roman Republic of 1849, the Risorgimento uprisings and 1898), landscape, exploration and travel from the Ottoman Empire, to India, China and Japan. Among the notable funds, in addition to the Iconographic Collection, on the historical and artistic heritage of Milan and Lombardy, and the Beltrami Collection, dedicated to the history of Milan and the Castello Sforzesco, appear: the collection of nineteenth-century photographs of Lamberto Vitali (1896-1992), the first scholar of Italian photography, together with the collection of photographs he took; the Leopoldo Metlicovitz fund; the Boschi Di Stefano fund; the Antique Slabs fund; and the Henri Cartier-Bresson fund. Donations have greatly enriched the holdings: among them, those of Gianni Berengo Gardin, Cesare Colombo, Mario Cresci, Giampietro Agostini, Tancredi Mangano, Francesco Giusti, Francesco Radino, Ugo Zovetti, and the important archive of Aldo Ballo and Marirosa Toscani. The Institute has also had on deposit since 2008 the Paolo Monti Archive (through an agreement with BEIC Foundation) and since 2016 the Carla Cerati Archive (through an agreement with her heirs).