There's an extensive book list on the sidebar. But it's all print books. Most of them are not available in digital form. I really don't want to collect massive tomes of history books, but I'd like to learn more about history.
Could there be a list of good history books that are available in an ebook format?
Try to post a variety of free historical texts in /r/freeEBOOKS :) some of those may be of interest to you. You can use the links in the sidebar there to sort by genre.
Just FYI, if you're in the US, most libraries can get you almost any book through an interlibrary loan. I've done this for many obscure books and while it might take a few weeks to come in, it's cost me $1 at most.