Rome: Why let the facts spoil a good story?

In a week when all eyes are on Athens, it feels a bit odd to be thinking about Rome. The two cities have, in one way or another, contended for title of Our Cultural Home for the last thousand years: longer, if you take the Roman Catholic Church into account.

Athens's claims are for architecture, democracy (in reality, a very limited system which wouldn't pass today), theatre and, above all, philosophy: a small, often-beleaguered city-state which managed to find enough time to ask itself: How should a man live?

Rome's claims are more brutally pressing. Conquest, expansion, trade, depravity, social mobility, corruption, and, above all, perhaps the greatest and certainly the most influential Roman invention of all: power.

The Romans wanted what lay beyond the horizon: things they couldn't even see. And the modern world is more Roman than Greek, and nor are today's Greeks the descendants of those Athenians queueing up to see Oedipus Rex 2,500 years ago.

So Robert Hughes's new book, Rome, is, in that sense, timely. As you'd expect from a great art critic - a man who has, you might say, popularised the science of seeing - Hughes's Rome is a city of the visual: of the piazzas and sculptures, the fountains and bronzes and paintings and the extraordinary attention to what, now, accountants would dismiss as unproductive detail but which, as Hughes point out, distinguishes a city from just a collection of buildings.

If London is the greatest city of all, then Rome is certainly the most concentrated.

Hughes's Rome works backwards from its art. The spiritual core of the city is, for him, the Campo dei Fiori - the "Field of Flowers", or perhaps the goddess Flora's Field - in which stands a statue of Giordano Bruno, burnt alive for challenging the Vatican authority by suggesting the universe was infinite and the earth, astronomically at least, nothing special.  

Heresy, disputation, power, bloodshed and monumental commemoration; and now a square buzzing with the flower and vegetable market during the day and the conversation of tourists and the young at night. It's a good, and symbolic, place for the centre of Hughes's survey.

The book, of course, has its deficiencies. One prominent critic - and passionate classicist - declared himself so distressed by half a dozen historical errors, found on opening the book at random, that he simply stopped reading the book.

You can see his point. One of Hughes's mistakes was to write that Augustus's successor was Tiberius, his son by his wife Livia. Actually, Tiberius's father was Tiberius Claudius Nero, Livia's first husband. And so Tiberius is remembered not only as one of the greatest cuckolds in history, but also, with a splendidly Roman irony, as the actual father of what we now think of (though they didn't) as a great dynasty of emperors.

On the other hand, the line of succession was less important to the Roman empire than it instinctively now seems to us. They didn't want kings. They didn't want the bloodline. Adoption, acclamation, the laying-on of imperial hands: these were enough. If a society can be said to have a collective desire, Rome's was for the best man for the job. The job was stability at home and power abroad.

If that desire led to the extraordinary testing of the limits of what an Emperor could not only do, but be - think of Caligula, Nero, the slit-mouthed Domitian, Tiberius on Capri with his swimming-pool full of pre-pubsecent 'minnows' - it also led to an indefatigable explosion of cultural innovation.

Art, architecture, engineering, the arts of war, sex, snobbery, luxury, food, money, money and more money: Rome was a terrible dynamo of fecundity and greed. And Hughes's point is that this fecundity - and the corruption that goes with it - somehow persisted, after a hiatus following the sack of Rome by the Goths in the early 5th century AD (oddly not really mentioned) through the Renaissance, under the patronage of the hugely powerful, and proportionately corrupt, Roman Catholic church, through until the 19th century, when a sort of strange exhausted stasis settled upon the place and remains to this day.

In the end, the critic who flung - or perhaps simply calmly placed - Hughes's book aside did himself a disservice. It's not a classical history and the errors of fact (if there ever is such a thing in ancient history) don't undermine its purpose, which is to show us Rome as made manifest in its public art and architecture: texts in stone and bronze and gesso and every other material you can think of, which speak of plutocracy and heirarchy, of God and Mammon, of power and vulnerability and bureaucracy, of conquest and decadence.

The wonder is, not that Rome has fallen into an ancient quietness, dependent on sleek politicos and gasping tourists, but that it managed to get away with it for so many centuries. And Hughes offers a glimpse of at least one of the tricks up its immemorial sleeve: the immense power of the image.

• Rome by Robert Hughes, Weidenfeld & Nicolson. ISBN 978-0-297-84464-8 ·