The Italian Painting collection is made up of over 150,000 photographs of painting from 12th to 20th centuries.
It is considered one of the most important, privately formed collections on Italy's painting heritage.
 
It follows a purely personal arrangement reflecting Zeri's working method and studies. Some sectors like that from 13th to 16th century are unique in their kind in quantity and quality of images, and an essential reference point for all researchers in the field.
 
Works that are now missing or damaged beyond repair are only to be found documented in the Zeri archive. In many cases he collected more than one photo taken at different times. He would track down and document on film the history and ‘ups and downs' of every single work, further rendering the Zeri Photo Archive a precious font of information.
 
For some works or important painting cycles, the archive contains entire photographic campaigns reproducing all the details of paintings and often documenting historical restoration work. Noteworthy examples are the series on frescoes with the Apocalypse stories in the crypt of Anagni Cathedral, and the Bardi and Peruzzi Chapels painted by Giotto in Florence's Basilica of Santa Croce, documented before they were restored in 1958-1961.
  
One editorial rarity is the important print series of The frescoes of St. Francis' life and The frescoes of the Old and New Testaments in the upper Church of the Assisi Sanctuary, photographed by Giulio Bencini and Mario Sansoni, edited and published in the 1940s by Pietro Toesca for the series Artis Monumenta Photographice Edita.
 
Over the years Zeri saved from dispersion and destruction entire photograph archives. Some of the most noteworthy collections come from scholars like Evelyn Sandberg VavalàUmberto Gnoli, and, in the case of architecture, Antonio Muñoz and Guglielmo Matthiae. The photograph collections of antiquarians include the Fritz Mont archives from New York, Sestieri and Sangiorgi from Rome, Longari from Milan, and Pospisil and Semenzato from Venice, all offering a cross-section of the history and taste of collecting in the 20th century.
 
Many photographic campaigns are by photographers practicing across the turn of the 19th century who made history in the photographic documentation of Italian art: AlinariBrogi and Sansoni from Florence, AndersonVasari and Moscioni from Rome, Villani of Bologna, and many others.
 
What makes the collection still more precious are the annotations in Zeri's hand on the back of photographs, and the numerous jottings, letters, surveys, and articles enclosed with them – all fruit of his tireless research or the anecdotes of collectors and antiquarians with whom he was in touch. This all forms a precious source of information rendered available in the Zeri Photo Archive.