I just ordered the book Washington: City and Capital published by the Federal Writers Project of the Works Progress Administration. The book was the Washington, D.C. edition of a series of books on each state published by the WPA. Although supposedly a guide, at 1,140 pages there’s clearly quite a bit else that made it in. This PDF guide on the series calls the book “one of the most interesting American Guide Series volumes. I just bought a copy for $30 off Alibris (complete with maps!), when it comes I’ll try to post something more about it.
If you’re interested, it looks like you can read the book online here.
Also, just found that H-DC has this 50 Essential Washington, D.C. History Books