i either didn’t find it interesting when i learned this in school… or i was never taught it.
there used to be only 10 months, but it wasn’t lining up as well as they would have liked to the agricultural seasons and lunar cycles. which is why dec (10) ember, nov (9) ember, oct (8) ober, sept (7) ember…. so an extra month was added… and then another one. july was added and was named over julius caesar… then augustus wanted a month. but august couldn’t have more days than july (the horror!), so days were rearranged and february had a couple taken that would be replaced every 4 years to keep it straight. right. anyway.
wikianswers is my source, so take it for whatever you’d like. and if you really know, then please, do tell.