Bashkir switchman on the Trans-Siberian Railway near the town of Ust-Katav, Russian Empire; ca. 1910
Taken by color photography pioneer Sergey Prokudin-Gorsky. He had an interest in documenting early 20th Century Russia through photography, but also enjoyed photographing others as well.
(For more of his fantastic work, take a look at the Wikimedia Commons page about him.)