Free Maps at the Library of Congress

They have more old maps than you can shake a theodolite at! I was looking for a map of Baltimore County, MD. so that I could locate the home of Major Harry Gilmor CSA where he grew up before the Civil War, and managed to find it ONLINE and save the web address. Now I know that the ruins of his home lie under the waters of Loch Raven Reservoir where Dulaney Run once flowed.
It may not be as much fun as handling and studying old maps, but it is definitely in Second Place since these old maps are all but unavailable. Check it out!

To keep this group from falling dormant, I thought I'd update this old thread with the relevant link, which is still available:
https://www.loc.gov/maps/