Peoples, why are we saying 'calendar'? This discussion is regarding the system of years, not about the ordering of months and days, or am I mistaken? For the calendar we use it, if I am not mistaken, very much based upon that of the Romans. After all, we have a month named for Janus, the last four named for the numbers seven, eight, nine, and ten, and two for Emperors, July and August. I think 'system of years' is a better term.
There shouldn't be any huge reason for Porre to change the calandar, as far as I'm concerned. Just because an empire falls, donesn't mean you gotta change the system. The roman empire fell how long ago? It was like 40 A.D., right? No one seemed too eager to change it.
As someone has already said, Rome did not fall in 40AD. In fact, it was nearing the height of its power in those years. I can't rightly remember, but I do think that 40AD was during the reign of Cladius, who was a good emperor following on the heels of the mad Caligula (and destined to be succeeded by the nearly as mad Nero, who was the last of the Julio-Claudians.) After that, we have the Flavians, which include Vespasian, Titus, and Domitian. Their reign lasts in the the early 100s. From then to the year 182 we have the Antonines, most well known being the conquerer Trajan, Hadrian, and the last two: Marcus Arelius and Commodus (who reigned 168-180 and 180-192 respectively.) After this there was some discord, with the military attempting to insert their own emperors, which I think eventually happened, as the next group were named the Severans. These lasted until the 200s, when there was a period of great disarray in the Empire. Finally order was restored under the Ilyrian emperors, the last of whom was wicked Diocletion. In the early ears of 300 (304, I think) a general named Constantine arose to rule the Empire, and it became Christian. But the fall could not be averted for long, and the last of the western emperors, Romulus Agustus, abdicated in the mid-late 400s to the barbarian king Odovacar - and, as Aitrus said, the eastern, Byzantinian empire, lasted until nearly 1500.