Now three other powers are vying to take their place: the media, the Church, and what claims to be the power of reason. The choice that some 112,000 Romans have to make this weekend in many ways encapsulates the Italian general election campaign.
Silvio Berlusconi, television tycoon and right-winger who wants to save Italy from Communism, suave communicator and Milanese, has opted to stand for election in Rome One, the constituency covering the mellow old heart of the city. Was it really, as his supporters say, 'because it is difficult', or have his whiz-kids in Milan made an error?
His radiant image, which beams out from posters and television screens, may well fail to work its magic here. The people who live in these cobbled alleys and stately palazzi - the rich, the civil servants, trendy intellectuals, priests and nuns, tradesmen, artisans and the popolino, the little people, with their rough dialect and centuries-old cynicism - could deal Mr Berlusconi's soaring ambitions a rude blow.
You could be forgiven for assuming otherwise. When he visits, which is rarely, many flock to see the great man on walkabout. 'It's him they want,' says a campaigner for his Forza Italia movement. Surrounded by his own heavies - he prefers them to a police bodyguard - he chats and jokes, enchants the children, visits all the right places; women kiss him, men want to shake his hand. The arch-conservative 'black' - or papal - aristocracy has given him its blessing.
In Via Laurina, one of his campaign offices, brightly coloured, expensively produced campaign material is piled high; bright, energetic yuppies are answering phones and carting out piles of leaflets. 'There has never been such enthusiasm in elections before,' says Ruggero Scoma, a young real estate consultant. Shopkeepers especially, the nearby antique sellers, art dealers and boutique owners struggling against the political and economic recession, will vote Forza. But, in spite of his own optimism, Mr Scoma acknowledges that Mr Berlusconi has a tough fight on his hands.
It might be thought that the Catholic Church, which ruled the city for centuries and until recently was able to shepherd large numbers of Italians away from the Communist wolf and into the ruling Christian Democrat (DC) fold, would be the power to defeat Mr Berlusconi in Rome. But it is not.
In Piazza Farnese Alberto Michelini, candidate for the centrist Pact for Italy, a Roman, active Catholic and member of the ultra-conservative Catholic organisation, Opus Dei, is scheduled to meet children and old people at four o'clock. An hour has passed, the sun is sinking behind the houses, supporters hold up banners in praise of the family and distribute leaflets to the odd tourist. But there is only one child, seven-month-old Stefano, asleep in his push-chair and not a single old person in sight.
'I'm not going to give a speech, just talk to ordinary people, passers by,' says Mr Michelini, a former television presenter, looking uncomfortable. But the only people he can find are his own well-dressed supporters. 'He does not have any chance around here,' says the news vendor across the square, who declines to give his name. 'He used to be DC.'
ALMOST nobody listens to the Church any more. Its close and uncritical association with the ultra-corrupt Christian Democrats dealt the final coup de grace to its already dwindling influence in politics. Now even the bishops no longer call on the faithful to 'maintain Catholic unity' - which meant 'Vote DC' - not least because there is no DC or any single Catholic party any more. Their pronouncements are limited to indicating a preference for the centre, although they still demand 'moral unity' of all Catholics when it comes to issues such as abortion and euthanasia.
Mr Berlusconi has written to the parish priests of Rome suggesting that in order to keep out the left, their flocks' votes would be best given to him rather than Mr Michelini, which the latter protests is a dirty trick. It will probably make little difference. 'The Catholic vote is a myth. It hardly exists,' Mr Michelini says. 'Mine is a vote of opinion' - meaning that his appeal lies in his centrist views. He is expected to poll between 10 and 14 per cent.
The real threat to Mr Berlusconi comes from a man who has none of his money, infrastructure, communications skills, bonhomie, charisma or even his looks. 'And none of his debts,' he would add, pointedly.
Luigi Spaventa is an economics professor, the Budget Minister in the outgoing transitional government and the candidate for the left, although he seems a remarkably conservative leftist. Mr Spaventa says it was principle that spurred him into running: someone, he felt, had to unmask Mr Berlusconi's promises of lower taxes, more jobs, higher pensions and a smaller state deficit.
'Vote Spaventa - vote for Reason', 'Vote Spaventa - vote for Truth', go his slogans. Cambridge-educated, a Fellow of All Souls, Oxford, married to an Englishwoman, he wears English-style suits or grey chalk-stripes and a seemingly English reserve. Street campaigning is, perhaps, not his forte.
But perched on a table in a meeting-room below a bar near the Piazza di Spagna, he reels off endless figures to demonstrate that Berlusconi's policies will not work. He is on his home ground. He holds forth on questions of labour mobility and ways to sort out the health service, complex problems of a modern state whose development has been warped. 'A new Italian miracle,' Mr Berlusconi promises. 'Miracles can't be done,' Mr Spaventa retorts.
Financial discipline is not the most obvious way to enchant tax-bruised Romans, but the Spaventa campaign seems to work. 'He is a famous professor, his name really means something around here,' says a blonde woman who has been listening with rapt attention. The grand bourgeoisie and the tradespeople may not like him, but the stallholders and streetsweepers on Campo de' Fiori market, the chic radicals and probably many learned colleagues will give him their vote.
'Spaventa who? Spaventa who?' Silvio Berlusconi replied when asked about his opponent one day, affecting not to know who he was. Professor Spaventa has challenged him to a face-to-face duel, certain that he could beat him on the economy and his companies' huge debts. But Mr Berlusconi refused, saying dismissively that the professor should first build up a commercial empire as he had done, and then apply again.
Even if he loses the battle for direct election in Rome, Mr Berlusconi will still get into parliament in one of the seats that are awarded to parties according to their proportional strength. But it will be a great personal setback. A man defeated in his own constituency would hardly be able to claim that he should be the next prime minister of Italy.