A wonderful online exhibition at the Library of Congress which gives access to the 19th century photoraphic collection of Prokudin Gorskii. Many images have been recreated in color (information on the process is also available on site). Site is in English.
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The Treasures of the Czars is a "virtual museum tour" brought to you by the St. Petersburg Times and The Florida International Museum. It is designed to give you a taste of the actual exhibit that includes more than 250 artifacts from 300 years of Russian history. Great images and graphic design. Worth visiting.