Alex Boese in LiveAboutDotCom –
Blame It on Augustus.
The Ancient Romans used to follow a calendar that had 355 days a year, but it eventually grew hopelessly out of sync with the seasons, making it difficult to celebrate festivals at the same time each year.
So in 45 BC, Julius Caesar decreed that a new, reformed calendar would be adopted that had 365 days a year, with an extra day every “leap year” in order to keep the seasons and calendar properly in sync.
However, the Roman priests who devised the new calendar initially made a mistake. They set the leap year to occur every third year. The priests realized soon enough that this wouldn’t work, and in 8 BC Emperor Augustus officially corrected the calendar so that leap years came every fourth year.
