Romulus and Remus were twin brothers. Their father was Mars, the God of War, their mother was Rhea Silvia, a vestal virgin and daughter of the King of Alba Longa, Numitor.
Numitor's brother, Amulius, had taken the throne from him and had forced Rhea Silvia to become a vestal virgin so that she would not have any children who might try to take back the throne.
When the boys were born, Amulius seized the children, He hoped that they would drown. However, the boys were rescued by a she-wolf who fed the babies with her own milk and cared for them.
They grew up and were found by the shepherd Faustulus, who took them home and looked after them until they were grown up.
The two young men decided to kill Amulius and put their grandfather back on the throne. After doing this they decided to build a city of their own away from Alba Longa but could not agree where to build it. Remus favoured the Aventine Hill but Romulus wanted to use the Palatine Hill. They could not reach an agreement and so each began to build his own city enclosed with walls.
One day, Remus visited Romulus and made fun of his wall by jumping over it and saying how easily it could be breached. Romulus was so annoyed that he killed Remus and said the he would kill anyone who mocked his city or tried to break through the walls of Rome.