Lives . Other major works of Imperial times were that of Livy and Tacitus. Polybius – The Histories Sallust – Bellum Catilinae and Bellum Jugurthinum Julius Caesar – De Bello Gallico and De Bello Civili Livy – Ab Urbe Condita Dionysius of Halicarnassus – Roman Antiquities Pliny the Elder – Naturalis Historia