I am currently reading (slowly) Tacitus’s Histories and Annuls. Fascinating and sobering. Ancient Rome has lots of parallels to Washington, D.C. (And you don’t have to strain your imagination to see them.)
Another one (and it’s one of the largest surviving ancient works, if memory serves) is Diodorus Siculus, a Greek historian who was contemporary with Julius Caesar and on into the time of Augustus.
https://search.brave.com/search?q=diodorus