Well, there's more to it than that: the leap day is really February 24th; there are "two" February 24ths. > Except that isn’t exactly true. The Romans did not

Well, there's more to it than that: the leap day is really February 24th; there are "two" February 24ths. > Except that isn’t exactly true. The Romans did not add an extra day on February 29, but on February 24, which is where the more complicated answer begins. The Romans kept a calendar by counting backwards from specific set times of the month, the kalends (March 1), the nones (March 7) and the ides (March 15). Julius Caesar was famously told in Shakespeare’s play to: “Beware the ides of March,” also known as March 15, the day of his murder. > If the Romans started counting on the first day of March, which they called the kalends and moved backwards, then their days would progress retrospectively like this: the kalends is March 1, second kalends is February 28, third kalends is February 27 and so on until February 24 is the sixth kalends of March. On a leap day, they added a second sixth kalends of March, which they called the “bissextile day”, that is the second sixth day. In older writings of various kinds, you will still see people call the leap day, February 29, the bissextile day. What the article doesn't explain, and I don't know either, is why they chose the sixth calends of March specifically, because there are "higher" calends, so it's not really the natural place to stick it. The Romans actually added January and February to the beginning of the year very early on, according to Livy, in the time of King Numa, second legendary king of Rome. The article doesn't mention this, but even during almost all of what we know as Rome, the months were numbered wrong! ed: what a mess! the answer appears to be here: https://www.google.com/books/edition/Johnson_s_Universal_Cyclopaedia/JgFJAQAAMAAJ?hl=en&gbpv=1&dq=%22Seventh+calends%22&pg=PA665&printsec=frontcover https://www.google.com/books/edition/Johnson_s_Universal_Cyc... Basically, the last days of February were already "past" the end of the religious year and placed in a special intercalary period, so the sixths calends of February was the last day of the "real" religious year in his time, which did not end at the same time as the business or calendar year. I think. This source also claims Caesar put January at the beginning of the year, which I am fairly sure is not correct. ed2: apparently authorities differ on month ordering timelines: Wikipedia cites Plutarch (not Livy) as saying it was King Numa who placed January at the begiining, Livy placing it centuries later during the late Republic, and others putting it in the time of the decemvirs, but I think it is still the case that even after the ordering was done the religious observances for the "end" of the year continued to take place in the beginning of the calendar year.