Historic week looms for Vatican with papal resignation

Pope Benedict XVI's final Sunday prayers in St Peter's Square will signal the start of a week in the Vatican that will make history with the first voluntary papal resignation in more than 700 years.

Tens of thousands of pilgrims have gathered in Rome from around the world following the ageing pope's shock announcement that he would step down because he no longer had the strength of body and mind to govern the Catholic Church in modern times.

Crowds are expected to turn out in the Vatican on Sunday and again on Wednesday when the leader of the world's 1.2 billion Catholics will bid a final farewell to ordinary Catholics at a general audience in the Vatican's 17th-century plaza.

On Thursday, the pope will meet his cardinals in the morning and take a helicopter to the papal summer residence of Castel Gandolfo in the afternoon.

The pope will likely continue his theological research but the Vatican has said he could also provide "spiritual guidance" for his successor.

The Vatican's culture minister, Gianfranco Ravasi, even likened the idea of the former pope in his hilltop monastery to the Biblical figure of Moses interceding with God on a mountain as battles raged in the valley below.

Immediately after the resignation, cardinals will hold conferences known as "congregations" starting on Friday that are a way of identifying priorities for the Church and sussing out viable candidates for the papacy.

In the interim before the election of a new pope, the Church will be run by Cardinal Tarcisio Bertone -- a divisive figure who has been Benedict's right hand man for years.