I'll second Tom Holland. I read "Rubicon" not too long ago. I would recommend pairing it with Dan Carlin's Hardcore History podcast series on the era for an extremely cohesive and engaging account of the Roman republic's decline.
Loved Persian Fire, in the middle of Rubicon right now as well. Excellent call on the Hardcore History - King of Kings three part (13 hour!) podcast. Listened to this falling asleep in my hammock on a backpacking trip for a week, amazing.
