What event marks the beginning of the Gregorian calendar? the birth of Jesus
the flight of Muhammad
the creation of the city of Rome
the rebuilding of the city of Medina

The birth of Jesus marked the beginning of the Gregorian calendar.

This calendar is a solar calendar system that is named after Pope Gregory. It is named after him because he was the one that issued the reformation of the calendar.

The calendar marks events as either A.D, or B.C. Each of these is traced to events before the birth of Christ or in the year of Christ.

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uncle sam would be tossing and turning in his grave : *)

to make world peace not vileonce with fist but words