This is not so much a recommendation for an ebook on historical fiction. In fact these would be terrible on the readers that most of use.
But if anyone has much of an interest in the "history" around the time of the story that you want to read, let me recommend the Historical Atlases from
Penguin.
I have some that appear to no longer be available. "
The New Penguin Atlas of Medieval History" still is though and is very good for gaining a feeling of the times.
"
The Penguin Historical Atlas of Ancient Rome" is another good one for anyone interested in ancient Rome.