Rome is founded based on a legend it is told that Romulus and Remus the twin sons of Mars, the god of war found the city. It is named Rome because when Remus was killed by Romuls he named the city after him.
The last king is overthrown and now Rome is officially a republic. Rome is now ruled by senators (elected officers) . In Rome there's now a constitution with laws and a complex republican government.
Hannibal invades Italy, Hannibal leads the Carthage army in his famous crossing of the Alps to attack Rome. This is part of the Second Punic war.