Pope Benedict XVI officially resigns as head of the Catholic Church today.

He steps down after nearly eight years in the papacy and will spend his retirement in prayer and reflection.

Over a hundred cardinals bid farewell to the Pope at a gathering in the Clementine Hall in the Apostolic Palace this morning.

In the afternoon, Benedict will depart his Vatican apartments and fly by helicopter to his summer residence, Castel Gandolfo.

He will make a final brief appearance to the public on the balcony at around 4:30pm.

The Swiss Guard will stand aside at 7pm, the time when Benedict officially ceases being Pope.

After this time, he will have the official title of Pope Emeritus and continue to wear the white cassock but without the cape.

His retirement will be lived out away from the world in a monastery in the grounds of the Vatican.

In the period until a successor is appointed, leadership of the Church will be assumed temporarily by Cardinal Tarcisio Bertone.

Around 150,000 people packed into St Peter's Square on Wednesday for the Pope's final general audience.

He thanked the Catholic faithful for their support and admitted there had been difficulties during his papacy, which was overshadowed by abuse scandals.

Benedict also thanked Catholics for respecting his decision to resign, saying it had been taken "in full awareness of its gravity and novelty but with profound serenity of spirit".

Cardinals will meet from Monday onwards to set a date for the conclave to appoint Benedict's successor.