The Autochrome Lumière photography process was developed by Auguste and Louis Lumière in France from 1904 to 1907. An early form of color photography, an image was taken using multiple color filters, red, green, and blue, to create a full-color image on glass plates. These specialty color plates could be used in existing cameras of the day, not requiring any additional equipment.
I find autochrome color photography to be uniquely beautiful, and very overlooked.