Sacred to Janus, the two-faced Roman god of doorways — fitting for the month between old year and new.
The first month of the year in the Gregorian and Julian calendars, consisting of 31 days.
From Latin 'Iānuārius' (mēnsis), the month dedicated to Janus, the Roman god of beginnings, transitions, doorways, and endings. Janus was depicted with two faces looking in opposite directions — one toward the past and one toward the future — making him the perfect deity for the month that opens the new year. The month was added to the Roman calendar by King Numa Pompilius around 713 BCE, when he reformed