This online exhibit from the Library of Congress (LOC) features a selection of photos by Sergei Mikhailovich Prokudin-Gorskii (1863-1944). In 1909-1912, and again in 1915, Prokudin-Gorskii undertook a photographic survey of eleven regions of the Russian Empire, traveling in a specially equipped railroad car provided by the Ministry of Transportation. Prokudin-Gorskii left Russia in 1918, and in 1948 the Library of Congress purchased from his heirs this unique collection of images of Russia on the eve of revolution. For this exhibit, the LOC has made color prints from the original negatives, which in fact, follows the photographer's original intentions. As the site notes, Prokudin-Gorskii invented a technique to show his images in slide lectures using a light projection system equipped with colored filters. The exhibit is divided into four sections: Architecture, Ethnic Diversity, Transportation, and People at Work. The images are offered as large thumbnails and accompanied by some explanatory text. The photos themselves are fascinating and expertly produced, almost indistinguishable from a new photo except in their subject matter. Well worth a visit.