Saturnalia was an ancient Roman festival in honour of the god Saturn, and according to our current interntionl calender it is held each year on 17 December. Later the festivities were expanded through to 23 December, thus covering the Winter Solstice.

The holiday was celebrated with a sacrifice at the Temple of Saturn, and then a public banquet, which was followed by private gift-giving. It was marked by tomfoolery and reversal of social roles, in which slaves and masters ostensibly switched places. This festival overturned Roman social norms as gambling was also permitted.  This swapping of roles was something that continued in many parts of the world up until the middle ages.  

Roman Mythology

In Roman mythology, Saturn was an agricultural deity who was said to have reigned over the world in the Golden Age, when humans enjoyed the spontaneous bounty of the earth without labor in a state of innocence. The revelries of Saturnalia were supposed to reflect the conditions of the lost mythical age, not all of them desirable. The Greek equivalent was the Kronia.This was the popular feast commemorating the dedication of the temple of the god Saturn.