* General audience is last before pope resigns on Thursday
* Pope will first go to summer residence, then back to Vatican
* Cardinals begin pre-conclave meetings on Friday
By Philip Pullella
VATICAN CITY, Feb 27 (Reuters) - A huge crowd gathered in St Peter's Square on Wednesday to bid goodbye to Pope Benedict the day before he becomes the first pontiff in some six centuries to step down.
The pope was to hold his last general audience, which usually takes place in an indoor auditorium but was moved outside into the sprawling square to accommodate more people.
"He did what he had to do in his conscience before God," said Sister Carmela, from a city north of Rome, who came to the capital with her fellow nuns and members of her parish.
Many in the crowd, which streamed into the square across the Tiber River and along nearby streets, held up banners thanking the pope and wishing him well. They came from all over Italy and abroad.
"This is a day in which we are called to trust in the Lord, a day of hope," said Sister Carmela. "There is no room for sadness here today. We have to pray, there are many problems in the Church but we have to trust in the Lord."
Some 50,000 people asked for the free tickets but the crowd was larger and many people had to stand at the back. No immediate crowd estimate was available.
"He was very humble to do this," said Carla Mantoni, 65, from a parish in Rome.
"I understand why he did this. It was clear from the start that he was more at home in a library. A very good man but he realised in his heart that this was the right thing to do for himself and the Church and now he will pray, he will pray for all of us," she said.
Despite the praise and sympathy for the pope from faithful in the square, many catholics were stunned by his decision and worry about the effect it will have on the future of a troubled Church.
The Vatican has said that Benedict, who will move to the papal summer residence south of Rome on Thursday night when the papacy becomes vacant, will assume the title of "pope emeritus" and be addressed as "your holiness".
SHOES OF THE FISHERMAN
He will lay aside the red "shoes of the fisherman" that have been part of his papal attire and wear brown loafers given to him by shoemakers during a trip to Leon, Mexico last year. He will wear a "simple white cassock", Lombardi said.
His lead seal and his ring of office, known as the "ring of the fisherman", will be destroyed according to Church rules, just as if he had died.
The Vatican said on Tuesday that the pope was sifting through documents to see which will remain in the Vatican and go into the archives of his papacy and which "are of a personal nature and he will take to his new residence".
Among the documents left for the next pope will be a confidential report by three cardinals into the "Vatileaks" affair last year when Benedict's former butler revealed private papers showing corruption and in-fighting inside the Vatican.
The new pope will inherit a Church marked by Vatileaks and by child abuse scandals involving priests in Europe and the United States, both of which may have weighed on Benedict's decision that he was too old and weak to continue.
On Thursday, he will greet cardinals in Rome, many of whom have come to take part in the conclave to elect his successor.
That afternoon at 5 p.m. (1600 GMT) he will fly by helicopter to the papal summer retreat at Castel Gandolfo, a 15-minute journey south of Rome.
There he will make an appearance from the window of the papal villa to greet residents and well-wishers expected to gather in the small square.
That will be Pope Benedict's last public appearance.
At 8 p.m. the Swiss Guards who stand as sentries at the residence will march off in a sign that the papacy is vacant.
Benedict will move into a convent in the Vatican in April, after it has been restored.
On Friday, cardinals in Rome will begin meetings known as "general congregations" to prepare for the secret conclave that will elect a new pope.
This week Benedict changed Church rules so that cardinals could begin the conclave earlier than the 15 days after the papacy becomes vacant prescribed by the previous law.
The change means that the cardinals, in their pre-conclave meetings, can themselves decide when to start.
The Vatican appears to be aiming to have a new pope elected by mid-March and installed before Palm Sunday on March 24 so he can preside at Holy Week services leading to Easter.
Cardinals have begun informal consultations by phone and email in the past two weeks since Benedict said he was quitting.
(Reporting By Philip Pullella; editing by Barry Moody)