Between 1849 and 1851, J.G. Heck published a 10-part encyclopedia called Iconographic Encyclopædia covering a wide range of topics in science and art. Nicholas Rougeux, who likes to web-ify old works, restored Heck’s 13,000-plus illustrations and restructured the encyclopedia for the browser. All it took was hours of manual labor spread out over 13 months.
Read more about the process here.