Thanks to the sophisticated work of archaeologists, we now know more than ever about the diets, health and housing of Roman-era communities from Syria to the German frontier zone. While the lives of the vast majority remain inaccessible to us, the epitaphs of an African ex-slave who ended his days in northern Britain, or a musician from Asia who met a premature death in Rome, give tantalising glimpses of human mobility in the multicultural world of Roman imperial rule.

Yet there are individual Romans who have long been familiar. Mary Beard’s masterful study of Roman history begins with a dazzling account of one such man, Cicero, in the year he held the consulship (Rome’s most prestigious office) and the state faced a terrible political crisis, as a conspiracy led by a renegade Roman aristocrat was uncovered. Cicero’s speeches against Catiline have been a staple of classical education and a reference point for political orators. Catiline has served as a byword for subversion, but he has also been rehabilitated as a champion of the dispossessed – or at least as the symptom of a broken system rather than an incarnation of evil. Was Cicero right in ordering that Catiline and his associates be executed without trial? Beard underlines the difficulties of working out what actually happened, but she also highlights what was at stake, both in Cicero’s own time and later.

The majority of surviving accounts of early Roman history date from Cicero’s time and later, several hundred years after the city’s alleged foundation, but Beard is a wonderfully lucid guide to its murky beginnings, shining a spotlight on dark corners of the Roman forum and the disturbing frequency with which stories of sexual violence (the rape of the Sabines, the rape of Lucretia, the almost-rape of Verginia, averted only by her death) punctuate Rome’s political history.

At what point did Rome make the transition from being a rather undistinguished settlement on the river Tiber, poorer and less well connected than many of its neighbours, to being a superpower in embryo? As Beard makes clear, the empire was generated partly through the exaction of military services (rather than tribute) from subordinate allied communities, yielding a huge reserve of armed force, and in part through the competitive ideology of the Roman elite – every senator dreamed of processing through Rome at the head of a victorious army. But expansion put great power in the hands of individual commanders. It was the empire itself, Beard persuasively argues, that ultimately produced the rule of the emperors.

Beard presents a plausible picture of gradual development from a community of warlords to an urban centre with complex political institutions, institutions which systematically favoured the interests of the upper classes yet allowed scope for the votes of the poor to carry weight. We may think of the Greeks as the great originators of western political theory, but Beard emphasises the sophistication of Roman legal thought, already grappling in the late second century BC with the complex ethical issues raised by the government of subject peoples.

Structures and institutions are the dominant concern in Beard’s compelling analysis but it is constantly enlivened by gripping episodes such as the assassination of Caesar and illuminating details like the significance of Augustus’ signet ring. Central chapters focus on two key individuals: Cicero, in many ways the symbol of the Roman republic, and his younger contemporary, the enigmatic Augustus, architect of the autocratic regime that succeeded the republic. Letters and other documents also allow us glimpses of family life, of what it might mean to be a slave-secretary, of the experiences of Roman upper-class women.

Relations between the sexes could be political dynamite. Mark Antony was in thrall to Cleopatra – or so Augustus alleged of his rival. What claims, we might wonder, did Antony make about Augustus? And if the emperor Nero often figures in the top 10 “most evil men in history”, this may be more to do with his successors’ need to justify his fall from power than his actual behaviour. For the majority of inhabitants of the Roman empire, as is emphasised, it made almost no difference who was emperor.

Beard is ever alert to linguistic nuance, sharing with her readers the point of Roman jokes and nicknames, teasing out the significance of a board game or an epitaph. Artworks and literary texts played a critical role in articulating identities, communal and individual, and in making sense of power in the Roman world. Modern scholars may struggle to interpret these texts now, and though Beard is primarily focused on Rome, she does not overlook the linguistic and cultural diversity of the vast swath of territory over which the city ruled.

The widespread practice of inscribing texts on stone or bronze has preserved the words of bakers, minor magistrates and slaves, as well as those of imperial authority (Beard argues against more pessimistic estimates of literacy levels). The preoccupations of Rome’s 99% can be gleaned from Egyptian papyri, or messages to the gods on lead tablets. Ex-slaves in particular made use of funeral monuments to showcase their citizenship. Issues of identity and belonging were all the more pressing in a world where the majority of Romans had never been to Rome.

Beard makes us reconsider what we think we know about the Romans. Her book is not a seamless narrative of the rise and flourishing of the Roman empire, but a subtle and engaging interrogation of the complex and contradictory textual and material traces of the Roman world.

The most devastating critique of the Roman empire comes in an imagined speech put in the mouth of a British tribal leader (“they make a desert and call it peace”) and was penned by one of Rome’s most distinguished senators, the historian Tacitus. An anxiety about what exactly it means to be Roman seems to drive many texts of the period. This anxiety insistently resonates with the concerns of the early 21st century. As Beard explains, it is not that we should take the Romans as our models. But reflecting on the ways they perceived and organised their world is a valuable reminder that concepts we take for granted – the nation state, for instance – are the product of particular historical circumstances. And that in a globalised world, different forms of identity, of community, of attachment may succeed them.

• SPQR by Mary Beard (Profile Books, £25). To order a copy for £17.50, go to bookshop.theguardian.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min. p&p of £1.99.