Rain on a wedding in Italy is regarded as good luck - a blessing from above - and on 25 March 1957 when the six founding members of the European Union signed the first treaty in Rome there was a thunderstorm. In those days there was no need for extra security, no sirens and no outriders to escort the signatories to their appointment. Only a few spectators turned out with umbrellas to see what was going on.

This Friday 29 October sees the signing in Rome of the new European constitution in the same place but with a rather different agenda. Six hundred heads of state, diplomats, bankers and delegates are expected at the Palazzo Senatorio at 10.00 for the four-hour signing ceremony. More than 1000 people have worked to prepare for the event, including the restoration of the sumptuous rooms at the Campidoglio that will be used for the signing.

There will be 5,000 members of the security services on special alert all over the city, 31 ambulances, 3 first aid posts and a helicopter ambulance will be standing by.

45 buses and 200 cars will be employed to move the visitors around the city and Ciampino, Rome's military and civilian airport, will be closed for three days from 28 to 30 October.

Two lorry-loads of flowers will decorate the ceremony, and lunch for important signatories is being offered by President Carlo Azerlio Ciampi after the ceremony at the Quirinale Palace.

A total 9 million will be spent on this historic occasion and the weather forecast says rain, again.