Leap years were devised in Julius Caesar's time, to fix the pesky problem that Earth's year isn't exactly 365 days. But 15 centuries later, our calendars were still slightly askew.
December is named for the Roman word for "tenth". So, why is it the twelfth month?
We will get an 'extra' day this year, February 29. Where do these quadrennial liberties with our calendar originate?