Who invented the calendar that we use todate, with 7 days and 12 months?
Answer:
The calendar we use today is called the Gregorian calendar after Pope Gregory XIII, who introduced it in October 1582. This was a calendar that improved on the Julian Calendar, which had been used since Roman times and contained a number of mistakes and inaccuracies. The seven day week has been used since the time of the Babylonians, as many cultures measured their calendars off the phases of the moon, which is most easily done with a seven day week.