Pope Benedict XVI has lit a Christmas peace candle set on the windowsill of his private studio.
Pilgrims, tourists and Romans gathered below in St Peter's Square for the inauguration of a Nativity scene and cheered when the flame was lit.
Later, he will appear in St Peter's Basilica to lead Christmas Eve Mass.
The ceremony begins at 10pm (0800 AEDT) instead of the midnight start time, which was changed at the Vatican years ago to let the pontiff rest before a Christmas Day speech to be delivered from the basilica's central balcony.
