Around 1905, he formulated a plan to use the emerging technological advancements in color photography to systematically document the vast and diverse history, culture, and modernization of the Russian Empire. Outfitted with a specially equipped railroad car darkroom provided by Tsar Nicholas II, Prokudin-Gorsky documented the Russian Empire around 1909 through 1915. His photographs offer a vivid portrait of a lost world—the Russian Empire on the eve of World War I and the coming Russian revolution. His subjects ranged from the medieval churches and monasteries of old Russia, to the railroads and factories of an emerging industrial power, to the daily life and work of Russia's diverse population.