A previous post talked about sites where you could find, view and download high-resolution historical and modern maps. But there are also a number of worthwhile sites that, while not allowing high-res downloads, let you view historical maps online.
David Rumsey Map Collection: Probably the best-known online map site, with 15,800 maps viewable, including “antique atlas, globe, school geography, maritime chart, state, county, city, pocket, wall, children’s, and manuscript maps”. There are a number of different map browsing and viewing options, none of which I’ve ever been all that crazy about. Before you even think about using this site, make sure you set your browser and firewall to allow pop-ups from this site, otherwise you’ll go nuts. But once you get past those issues, there’s hours of map-browsing pleasure here.
British Library: Not surprisingly, very strong in historic maps, especially those of the British Isles and Europe. Check out the collections of scanned maps. Higher-resolution digital images of many of the maps are available for purchase.
New York Public Library: Large collection of online maps for NY, the US and the world, and (oddly enough) shaded relief military maps of the Austro-Hungarian empire. Prints available for sale.
Shaded relief map of Reichenburg and Friedland, Austro-Hungarian Military Geography Institute
Know of any other large online map collections? Let me know in the Comments section.