When the Roman emperor Hadrian visited Delphi in 125AD, he asked the famous oracle: "Where was Homer born and who were his parents?" You might have thought that the ruler of an empire that stretched from Scotland to Syria and probably included 60 million inhabitants would have had more weighty issues on his mind. After all, there had been conspirators trying to unseat him; there was more than the usual trouble with barbarians (hence, on some interpretations, his decision to build "The Wall"); and a major Jewish uprising was only a few years away.

Nonetheless, it was the family background of the first and most renowned Greek epic poet that was the subject of his inquiry. Quick-thinking, the priestess obliged: Homer was born on the island of Ithaca, and was none other than son of Telemachus, and grandson of Odysseus himself. This curious incident introduces the vast new (self-styled "epic") history of the classical world, both Greece and Rome, over 900 years from Homer to Hadrian, by Robin Lane Fox: Oxford classics don, huntsman, gardening correspondant and academic adviser on Oliver Stone's Alexander - not to mention a rider in one of its cavalry charges.

Lane Fox's basic message is that an enormous amount is lost in the split that most modern writers make between Greek history on the one hand, and Roman on the other. For a start, despite our usual assumption that Greek civilisation came first, the two cultures developed side by side: Rome, according to the Romans' own dating, was founded less than 20 years after the first Olympic Games.

More important, Greece and Rome were constantly interacting, and not just in that Greece was eventually swallowed up in the Roman empire. There were statues of Greek celebrities in the Roman forum from as early as the fourth century BC. And Rome's neighbours in Etruria were eager consumers of Athenian pottery from the sixth century on: the vast majority of "Greek" decorated pottery in our museums was actually found in Italy.

The emperor Hadrian represents the acme of that process of interaction. He was a Roman who more or less became a Greek. He sported a distinctively Greek-style beard; he was known for his "Greek love" of the beautiful teenager Antinous, whose sultry features he replicated in hundreds of statues littered across the empire; and at his "villa" at Tivoli outside Rome (a euphemism for what was a vast palace the size of a small town), he literally recreated the Greek world on Italian soil, with expensive - if somewhat theme-park-style - replicas of major Greek sights, monuments and works of art.

It is for this reason that Hadrian provides the linking thread through Lane Fox's great sweep. We are repeatedly told what Hadrian made, or might have made, of the events and cultures described: he was keen on Spartan values, ill-informed about Sicily, uncomprehending of the complexities of Roman civil wars. He is even introduced at the beginning as the book's "assumed reader".

Apart from this, The Classical World is, by no stretch of the imagination, a radical or particularly innovative account. It is a brisk narrative, which concentrates on the stuff of political and military history, as the chapter headings themselves make clear: "Tyrants and Lawgivers", "Alexander the Great", "The Rise of Julius Caesar", and so on. There is not much on anyone below the ranks of the elite. The nouveaux riches of Pompeii are rather sniffily dismissed for their vulgar tastes, while the Roman plebs are written off as "at bottom conservatives" (an extremely unlikely idea).