15 March 44 bc began tensely. Some four weeks before, the Senate, menaced by threatening mobs, had appointed the populist general Julius Caesar dictator for life. Now, in every place where people gathered – bath houses, market places, temples – the speculation was intense. Was this the end of the Republic that had lasted for more than four-and-a-half centuries? Would anyone stand up to save it and the liberties it guaranteed? Talk of assassination was common, but Caesar, scorning precautions, dismissed his guard and travelled in a simple litter to that day's scheduled meeting of the Senate in the Forum Romanum – a vast, rectangular meeting place, 200 metres long and 75 wide, bordered lengthwise by up-market shops and apartments, and endwise by government offices. At the northern end, dominated by a steep cliff leading to the Capitol Hill, stood the Tabularium (national archive); the Temple of Saturn (state treasury); the Temple of Concord; and the new Senate House (the old having been burnt down by rioting supporters of the murdered demagogue Publius Clodius eight years before). In front of the Senate House lay the Comitium, the political assembly ground where senators addressed citizens from the Rostra, the raised speaking platform made from the wooden prows of captured warships. Opposite, at the southern end of the Forum lay the Temple of Castor and Pollux, from which the tribunes addressed rowdy gatherings of the plebs, watched over by the club-wielding thugs of the city's various factions.

Caesar's view of Rome's heart would have been rather different to the one we are used to seeing in Hollywood movies; it was still ramshackle and brick, not yet replaced by the marble caricature of sham democracy that plutocracies prefer; Ridley Scott's computer-generated imperial city had yet to be built. The Forum – the epicentre of the Roman state – was still, above all else, a place dedicated to political speech. Riot, murder and factional mobs may have made it dangerous to enter, but in this arena the essence of classical democracy – persuasion – still had the potential to carry the day and, just possibly, change the future course of history, as Caesar's fatal entry to the Senate chamber was about to prove.