It’s January, the first month of the year, ruled by the god Janus, who looks both ways. But a week ago it was December, the…tenth month of the year? What the heck was up with Roman calendars? Join Em and Dr. Jesse to explore why this otherwise competent civilization just fell apart when it came to tracking what day it was.

Jörg Rüpke, The Roman Calendar from Numa to Constantine: Time, History, and the Fasti, Wiley-Blackwell, 2011.

1/ Rome’s famous AVC (or AUC today), the abbreviation for Ab urbe condita (from the founding of the city), i.e. 753 BCE.

2/ For example, archeology uses “BP” or “Before Present.” Geology and astronomy and similar tend to use variations on “millions of years ago“.

3/ Calends! Nones! Ides!

4/ December is such a mess! For more on December not being the 10th month of the year (maybe ever!)–and/or the possibility of competing new years (one beginning in January and one in March), see Rüpke (p. 6).

5/ Fasti Antiates Maiores, created 60s or 50s BCE (Rüpke, p. 6), from before the Julian reforms in 46 BCE. January is the first month. Here is the original and here is the reconstruction.

6/ Annus confusionis ultimus! (46 BCE) See Rüpke, p. 112.

7/ Gregorian calendar!

8/ England finally officially adopts the Gregorian calendar in 1750. (This was adopted for the whole British Empire, including the colonies in America.)