Anyone who is serious about their ancient history needs to know about the Loeb Classical Library which gives historians access to the original Latin or Greek text with an English translation on the facing page.
These small hardcover books are excellent editions that are accessible to anyone whether you have classical language skills or not. However, they don’t come cheaply, in Australia I pay an average of $55 per volume if I purchase them from a local bookstore. You can get them cheaper if you can wait by ordering them directly from Harvard University Press where they cost about US$26 each.
But the resource I wanted to bring to your attention today is Loebolus which contains a database of 273 older out of copyright Loeb volumes that you can download individually or as a bulk lot but it might take a while to download all 3.2GB worth.
This is an excellent way to start a high quality ancient history library.