Use these resources to start your research, to help you in picking a topic.
The Oxford Classical Dictionary by 
Ancient Greece and Rome : an encyclopedia for students
Encyclopedia of Ancient Greece by 
The World of Ancient Rome : A Daily Life Encyclopedia by 
The Oxford Encyclopedia of Ancient Greece and Rome by 
Chronicle of the Roman Emperors by 
The decline and fall of the Roman Empire by History of Greece, and of the Greek people, from the earliest times to the Roman conquest. by History of Julius Caesar ... by History of Rome, and of the Roman people, from its origin to the invasion of the barbarians. by 
A Companion to Greek and Roman Historiography by 
Greek and Roman Historiography by 
The Oxford Handbook of Roman Studies by 
The Oxford Handbook of Social Relations in the Roman World by 
The Oxford Handbook of Warfare in the Classical World by 
The Cambridge Ancient History by