Romulus and Remus were twin sons of Mars, the God of War. Their mother was a daughter of King Numitor. Numitor's throne was seized by his brother, Amulius. The twins were thrown out into the river by Amulius at birth, as he feared they would attempt to seize his throne.
The twins were taken in by a she-wolf, and the babies were fed with her own milk.
The boys were found and raised by the shepherd Faustulus, who looked after them until they were grown up.
The men found out who they really were, and decided to kill Amulius and place their grandfather back upon the throne.
Romulus and Remus parted ways and built their own separate kingdoms.
Remus visited Romulus, jumping over his wall and exclaiming how easily it could be breacher. Romulus was so angered by this that he killed Remus.
The two eventually formed an agreement. The legend ends with Romulus being carried into the heavens by his father, Mars, and he is worshipped as the God Quirinus.
War was declared on Romulus and the kingdom of Rome by the Sabine tribe, as Rome had been stealing their women to provide wives and slaves.