I've read and re-read the Poldark novels a bunch of times, I love it so much. Right now I can't remember the exact titles of books I have read that fit in the Byzantine time frame, but I know I've read a few. I think the reason I chose to write in English medieval is because that's where my base was. I am not a history major, but I love reading actual history books when a novel piques my interest.

California has very tall mountains of course...I am amazed by the fact that in our state we have the tallest peak in the continental US (ie: the states that are connected to one another) and a few hours drive away is the lowest point (below sea level) in all of North America. You could drive from the base of the Mount Whitney to Death Valley in the same day!