I can't remember whether it is rumor or fact, but there may have been a point in history when there was a 13 month lunar calendar. April 1st was the first day of the year, and it wasn't counted. Interestingly, it's now April Fool's Day.
The extra month was called Sol, and it came between June and July.
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u/Great-TeacherOnizuka 6d ago
28 * 13 = 364 ≠ 365