Start with the recent output of Anthony Everett:
Cicero, the Life and Times of Rome’s Greatest Politician
Augustus, The Life of Rome’s First Emperor
The Rise of Rome
Hadrian, and the Triumph of Rome
Add in the easier stuff by Tom Holland:
Persian Fire, the First World Empire and the Battle for the West
Rubicon, the Last Years of the Republic
Dynasty, The Rise and Fall of the House of Caeser
The Forge of Christendom, the End of Days and the Epic Rise of the West.
You might even start with his translation of Herodotus if you want early sources.
Lidell Hart’s Scipio is an easy intro to the Roman Hero of the Punic Wars.
O’Connel’s The Ghosts of Cannae: Hannibal and the Darkest Hour of the Roman Republic
Now let’s add in Victor Davis Hanson, not only a great historian but a good conservative essayist.
A War Like No Other
The Western Way of War
Carnage and Culture
The Father of Us All: War and History, Ancient and Modern
Paul Cartledge, Thermopylae: The Battle That Changed the World
(Read this after Holland’s Persian Fire which sets it in context better than anything else I have read)
My favorite early source is Polybius. Get a good cloth back edition of the complete Histories.
Add in Dying Every Day, Seneca at the Court of Nero by James Romm and you should have a good start.
Thank you for that list!!!