This temple has traditionally been believed to be dedicated to Janus, but this is not certain. Regardless, the Roman temple probably replaced a wooden temple to a Gallic deity that already stood on the site.
The Roman god Janus presided over war, gates, doors, doorways, beginnings, and endings. The month of January and the caretaker of doors and halls, a janitor, are both named for him.
Janus is usually depicted with two faces looking in opposite directions - one bearded and one clean-shaven - and holding a key. The two faces are believe to represent the sun and moon.
For the ancient Romans, Janus symbolized change and transitions such as the progression of future to past, of one condition to another, of one vision to another, the growing up of young people, and of one universe to another. He also represented time because he could see into the past with one face and into the future with the other.
Thus 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.