Around 1907 Prokudin-Gorskii envisioned and formulated a plan to use the emerging technological advancements that had been made in color photography to systematically document the Russian Empire. Through such an ambitious project, his ultimate goal was to educate the schoolchildren of Russia with his "optical color projections" of the vast and diverse history, culture, and modernization of the empire.
So, basically, color photographs of an era we're used to seeing in black and white. Neato!
I originally saw this just before the Library of Congress ran this exhibit back in 2001. There seem to be quite a few more images on the exhibition site then I remember. Library of Congress exhibition: The Empire That Was Russia.
As well, since I bookmarked a site about this back in 2001, a bunch of amateurs on the net have gotten ahold of the b&w originals from the LoC and used Photoshop to make more composites. They're generally not as good, but some of the subject matter is still interesting. The Russian Record: The Work of Sergei Mikhailovich Prokudin-Gorskii (1863-1944)
Hooray for keeping old bookmarks around for 5 years!