Dies Natalis Solis Invicti (Birthday of the Unconquered Sun)

Roman Imperial repoussé silver disc of Sol Invictus (3rd century)

Sol Invictus was the official sun god of the later Roman Empire and a patron of soldiers. In 274 AD the Roman emperor Aurelian made it an official cult alongside the traditional Roman cults.
Celebrated near-solstice
After his victories in the East, the Emperor Aurelian reformed the Roman cult of Sol, elevating the sun-god to one of the premier divinities of the Empire.
Constantine decreed (March 7, 321) dies Solis—day of the sun, "Sunday"—as the Roman day of rest (Codex Justinianus): On the venerable day of the Sun let the magistrates and people residing in cities rest, and let all workshops be closed.”
Constantine's triumphal arch was carefully positioned to align with the colossal statue of Sol by the Colosseum.
Celebration included religious rites and public business was suspended. Even slaves were supposed to be given some form of rest. Family and community celebrations were held.
Within the city of Rome, the priests were not allowed even to see work done.
Sol Invictus played a prominent role in the Mithraic mysteries, and was equated with Mithras.

So….what was Mithraism?

A mystery religion of the god Mithras practiced in the Roman Empire from about the 1st to the 4th century.
Mithras was born from a rock emerging already in his youth on December 25 (date contested by some)
Key imagery includes Mithra slaughtering a sacred bull while being watch by Sol who he then shares food with.
There are no written records of this religion, so all information has been interpreted by archeological evidence.
By some, Mithraism has sometimes been viewed as a rival of early Christianity with similarities such as liberator-saviour, hierarchy (bishops, deacons, presbyters), communal meal and a hard struggle of Good and Evil (bull-killing/crucifixion).
Mithraism declined with the rise to power of Christianity,
Early Christian apologists noted similarities between Mithraic and Christian rituals, but nonetheless took an extremely negative view interpreting Mithraic rituals as evil copies of Christian ones.

Métis in the City