The Photo Archive's two million photographs provide supplementary and original pictorial research for the study of fine arts from antiquity to the modern period. The archive's strength lies in the photographic reproduction of western art, architecture, and decorative arts.

Patrons can use these photographs to conduct a wide range of research, including the history of collecting (provenance, art market, connoisseurship), iconography, conservation, historiography, and the history of reproductions.