In Roman mythology, Janus (or Ianus) was the god of gates, doors, doorways, beginnings, and endings.
Janus was usually depicted with two heads (not faces) looking in opposite directions, and was frequently used to symbolize change and transitions such as the progression of past to future, of one condition to another, of one vision to another, the growing up of young people, and of one universe to another.
He was also known as the figure representing time because he could see into the past with one face and into the future with the other. Hence, Janus was worshipped at the beginnings of the harvest and planting times, as well as marriages, births and other beginnings. He was representative of the middle ground between barbarity and civilization, rural country and urban cities, and youth and adulthood.