December was the tenth month of the year after March, which was the first one on the old Roman calendar. The names of most months originated in this first calendar, with an uncounted gap from December to March when no agricultural work was done.

The Saturnalia (December 17-23) was a winter solstice festival to honor Saturnus as the god of seed sowing and recalled the "Golden Age" of Roman mythology when he ruled Latium at the beginning of the world. It was likely the most popular of all Roman festivals. Shops, law courts, and schools were shut; it was a time of relaxation and general merriment.

The festival opened with a great sacrifice at the temple of Saturn, the ruins of which are shown on the left. It was situated at the foot of the Capitoline hill and served as Rome's treasury. Within the temple was a hollow statue of Saturnus that was filled with oil. On the first day of the festival, the woollen bonds that fettered the statue were undone. Perhaps it was a gesture to retain both the presence of the god and his goodwill.