Polytheistic: Many were of Greek origin.
Consisted Patricians (land owning noblemen), Plebeians (all other free men), and slaves.
Government composed of a Senate and the Assembly.A republic, similar to the constitutional democracy in the US. Everyone votes for representatives and Congress votes on all the major issues.
Enemies: Carthage, Macedonia/Greece, Gauls, Spaniards
Collapse of the Republic: restlessness caused by overwhelming number of slaves, high rate of inflation, political leaders started fighting among themselves.
So, the power of the Senate weakened and were transferred to three men, the first triumvirate: Pompey, Crassus, and Julius Caesar. Civil war resulted and Caesar became emperor. But it didn't last long, he was assassinated in 44 BC.
After Julius Caesar died, a second triumvirate was formed composed of Octavius, Marc Antony, and Lepidus. Power again shifted to one: Octavius, who eventually assumed the name Augustus Caesar. No more Roman republic.
Under Augustus stability returned for the next 200 years: the Pax Romana.
Collapse due to internal decay (sheer size and bad leaders) and external pressure (Attila's Huns)