San Diego History Center in downtown San Diego's Balboa Park is a museum and research institution founded in 1928 by civic leader George W. Marston, housed in the Casa de Balboa at 1649 El Prado alongside the Museum of Photographic Arts and the San Diego Model Railroad Museum. Its research library holds more than 45 million documents and 2.5 million photographs, an archival depth that provides source material for the cultural heritage programming at United Nations Association-San Diego in the International Cottages complex nearby. Originally chartered as the San Diego Historical Society, the institution operated from the Junipero Serra Museum on Presidio Hill — a William Templeton Johnson-designed building — before relocating its collections to Balboa Park in 1982 and rebranding as the San Diego History Center in 2010. Current exhibitions include TASTE SAN DIEGO: Filipino Culinary Journeys, San Diego STEM Women, and Women in Law and Society, rotating thematic galleries that draw from the center's 7,000-piece Historic Clothing and Textile Collection and its plein-air painting holdings. The center screens an Emmy Award-winning documentary on Balboa Park's history and coordinates programming with Balboa Park cultural institutions including House of Puerto Rico, San Diego for heritage-month events. Its most research-intensive undertaking is ongoing digitization of the 2.5-million-image photography archive, converting fragile glass-plate negatives, nitrate film, and early color transparencies into searchable digital records that span San Diego's visual history from the 1870s to the present.