In the pre-Julian Roman calendar there were two cycles of festivals to mark the end of the year, in December and in February, and also residual elements of the decimal scansion of Roman metrology. Together, these elements confirm the traditional hypothesis of a year composed of ten months (the so-called ‘Romulian’ year) prior to that of twelve months (the so-called ‘Numan’ year). The ‘Romulian’ calendar was modified quite considerably during the times of the first Etruscan kings, associated with profound socio-political, and perhaps also metrological, reforms. From then, the two ‘missing’ months in the ‘decimal’ calendar, periods in which work would have been concentrated within the home rather than outside, with the exchange of the surpluses which had been accumulated, were incorporated. The new months were called Mercedonius (?) and Februarius, the latter being the last month of the year. A radical revision of the calendar, which resulted in the last two months becoming the first two, appears to have occurred at the time of the dramatic move to the Republic, as the old festival was too closely related to the figure of the rex. It can be concluded that the archaic calendar of Rome reflects a stratified series of various religious, political and ideological elements evolving over the centuries.