Saturnalia was an ancient Roman holiday held from December 17th or the first day of Capricorn, the house of Saturn and lasted from one to five days variously through its history. The celebration of Saturnalia continued into the 4th century C.E.
Like many Roman festivals, Saturnalia had public and private aspects. The public celebration took place on December 17th and consisted of a ritual sacrifice to Saturn at the Temple of Saturn in the Roman Forum. The statue of Saturn, which was usually bound with wool, had its bindings removed by priests who, contrary to usual custom, uncovered their heads for the occasion. After the sacrifice, the public was treated to a sumptuous banquet at which the statue of Saturn was a special guest, laid out on a luxurious couch.
The rest of the festival consisted of carnival-like celebrations throughout the city overseen in later years by the Saturnalicius princeps, a master of ceremonies chosen by lot whose job it was to make the festivals as unruly as possible. All of his ludicrous commands must be obeyed under penalty of humiliation.
Private celebrations included gift-giving, gambling, feasting and general partying and revelry during which social norms were not just relaxed, but overturned.
One particularly notable feature of the celebration was the role reversal of master and servant. One theory as to the nature of this festival points to a mythical Golden Age of man that was ruled over by Saturn and Ops during which all were equal, food was plentiful and no one had to work to survive.
Saturnalia is believed to be heavily influenced by the Greek festival Kronia.