Italy ground to a sombre halt as the state funeral took place of 19 Italians killed last week in Iraq.
Italy has been united in sorrow
The Italian president and prime minister led up to a quarter of a million mourners at a service also being attended by 25 injured survivors.
Many people in shops, offices and schools across the country also observed a minute's silence.
"The war was a far away thing before. Now it has come to Italy," said a mourner outside St Paul's Basilica.
Tens of thousands of people lined the streets and church bells tolled as the coffins of the dead were driven to Rome's second largest basilica for the funeral.
About 250,000 people watched the ceremony on screens outside the church.
Inside, the coffins were laid out in two rows before the altar, draped with Italy's red, white and green flag. On one man's coffin the family had put the shirt of his favourite football star.
The bombing last Wednesday was the deadliest single strike on international forces in Iraq, and the worst Italian military loss since World War II.
Nine non-Italians - most of them Iraqi civilians - were also killed when a suicide bomber rammed a petrol tank through the gates of the Italian base in the southern Iraqi city of Nasiriya.
Cardinal Camillo Ruini, the senior cleric officiating at the funeral, said Italy would not flee what he called "the murderous terrorists".
"We shall face them with all the courage, the energy and the determination we can muster.
The attack devastated the Italian base
"But we shall not hate them. On the contrary, we shall not tire to try and make them understand that Italy's entire commitment, including its military involvement, is oriented to safeguarding...space and dignity for all peoples, cultures and religions."
After his homily, the names of each victim was read out and to the mournful strains of a cello, the coffins were carried out of the basilica for burial. The assembled crowd outside applauded quietly.
Tuesday was declared a national day of mourning in Italy.
Schools observed a minute of silence, shops closed, and television stations are not running advertisements.
Across the city the national tricolour flew at half-mast from many public buildings and was hanging from the windows of many private houses.
The BBC's David Willey in Rome says the bombing seems to have united this often divided country, which has decided to suspend all argument about the rights and wrongs of the war in Iraq for a whole day while grieving together.
'Failure to understand'
In Iraq, an Italian with the US-led administration has quit his job blaming mistaken policies for the attack.
Marco Calamai said the Coalition Provisional Authority had failed to understand the complexities of Iraqi society.
He called on the United Nations to intervene in the country to improve a situation he described as "seriously compromised".
A spokesman in Washington, Richard Boucher, dismissed Mr Calamai's accusations saying the provisional authority had made excellent progress in Iraq.
A Senegalese imam branded a security threat is being deported
And a spokesman for the CPA, Charles Heatley, said Mr Calamai's views were not shared by the thousands of other members of the authority working in Iraq.
In a separate move, the Italian Government announced it would deport radical Muslim cleric Abdel Qadir Fadlallah Mamour, who warned there would be attacks on Italian soldiers in Iraq and of "terrorist" attacks in Italy itself.
Interior Minister Giuseppe Pisanu described him in a statement as "a danger to state security".