On 14 November Pope John Paul II will address the chamber of deputies, just a few weeks after he was made an honorary citizen of Rome; two apparently similar ceremonies which are actually very different.

The invitation from parliament was made in the last legislature and renewed by the present speaker, Pierferdinando Casini. It is the first time that a pope goes to the Italian parliament. The visit is obviously a sign of the cordial relations between the pontiff and Italian institutions, and it is hardly controversial.

The granting of honorary citizenship is definitely controversial and has much deeper implications. For once the hype about an historic event, as Romes mayor Walter Veltroni has called it, is not an exaggeration. From his point of view, he has brought a complicated diplomatic and personal negotiation to a satisfactory conclusion.

Veltroni wants to establish Rome as the city of peace and one that is concerned with world hunger aims which the pope shares. The idea of giving the pope honorary citizenship came to Veltroni after his audience last year. Apart from his global aims, the pope has had close contact with grassroots Catholicism here. After all, the pope is first and foremost bishop of Rome, though most of John Paul IIs predecessors have largely delegated that role.

In his 24 years as pope, John Paul II has visited 301 of the 335 Roman parishes and has supported the citys social policies. He has also declared that he felt a citizen of this town. And the mayor took him at his word.

For once, the whole city council agreed on a motion and the other side of the Tiber, as Romans call the Vatican, accepted. Or rather, it was almost certainly the pope himself who made the running, reckoning that the political and media advantages outweighed the diplomatic and historic downside.

The event is another step, in some ways the culmination, of the reconciliation between Italy and the Vatican that has taken almost a century and a half.

Times have changed since the spiritual head of Roman Catholicism was also the temporal ruler of Rome. Before Rome became part of the new Italian state in 1870, the papal guillotine stood and functioned in Piazza del Popolo or in the Forum Boarium (now Piazza della Bocca della Verit), a sharp reminder of where power lay. For venial crimes, if you look at those 18th-century plaques in the historic centre prohibiting the dropping of litter, you will notice that the ordinance is signed by the Most Excellent Monsignor of the Streets.

Even if many Catholics at the time felt that their leader would be more spiritual if he were not executing criminals and keeping the streets clean, Pius IX did not agreee. He refused to renounce his claims to temporal power even though in practice he lost it when the Italian bersaglieri came in through Porta Pia on 20 September 1870.

Instead, he ordered Catholics not to take part in the politics of the new kingdom either as voters or as candidates and he declared himself a prisoner in the Vatican. Pius IXs successors maintained the frost for almost 60 years, only fully recognising Italy with the Lateran Pact in 1929.

The more anticlerical elements of the new state lost no opportunity to snub the citys former rulers. Even Prati, which was built close to the Vatican soon after unification, is full of streets with resounding Risorgimento names like Piazza Cavour and Mazzini, or ancient Roman names like Via Giulio Cesare or even names of mediaeval populists like Cola di Rienzo but there is not a pope, priest or saint among them.

In 1887, the then mayor of Rome was dismissed by the prime minister Francesco Crispi for having dared to send Leo XIII greetings on his sacerdotal jubilee. Two years later, the city put up a monument to Giordano Bruno, a heretic executed by the Church. In 1892, the monument to Victor Emmanuel II grew over Piazza Venezia. The speaker of the senate, Domenico Farini, wrote in his diary: Italy has to put up something big to show the Vatican.

After world war one, Benedict XV finally allowed the formation of a Catholic political party and under Mussolini Church and state formally reached agreements on how to treat each other. Even so, in 1946 the Vatican warned the Christian Democrat prime minister De Gasperi not to work with the anticlerical parties in Rome and in the national government. The frost was back and did not begin to thaw until the pontificate of John XXIII in 1958.

The anomaly in Rome is that there is a foreign country on the west bank of the river which is at the same time the centre of Italys religion. When John Paul II speaks is it as bishop of Rome or as sovereign of the Vatican state?

When he visited the Campidoglio in 1998, it was only the second time that a pontiff had done so since 1870 (the first was Paul VI in 1968) and the first time that one had taken part in a city council session. So when he accepted the honorary citizenship, it was not just an honour bestowed on him, a recognition of his merits, as it was with Mother Teresa in 1996 or with Romes long-serving rabbi Toaff. He himself has recognised the legitimacy of the secular city government: a sovereign becomes, albeit symbolically, a citizen.

The occasion is all the more remarkable and indicative of the personal bond between the pope and the mayor because Veltroni has never hesitated to go against the Vatican line on matters of principle. He supported the 2000 World Gay Pride week in the city and has criticised the Churchs ban on condoms in the fight against HIV-AIDS.

Taken all together, then, the event surely deserves the epithet historic.