Pope Emeritus Benedict XVI is returning to the Vatican, to live alongside his successor Pope Francis in his retirement.

Benedict on February 28 became the first pontiff to voluntarily step down more than 600 years.

The 86-year-old German emeritus pontiff left the papal residence in Castel Gandolfo, in the hills south of Rome by helicopter on Thursday.

Benedict was last seen in public on March 23 looking frailer than when he left his at the end of the previous month.

Vatican spokesman, the Rev. Federico Lombardi, noted that the retired pope is not afflicted by any ailment.

"He is a man who is not young: He is old and his strength is slowly ebbing," Lombardi told journalists week. "However, there is no special illness. He is an old man who is healthy."

When he announced his retirement Benedict left the Vatican almost immediately after his resignation keeping himself away from the process of electing his successor.

The Vatican said Benedict will reside at the "Mater Ecclesiae" Monastery which has been undergoing renovation since November 2012, and until then was inhabited by Visitation nuns.

Pope Emeritus Benedict will reside with his secretary, Monsignor Georg Gaenswein, and four long standing staff members.

When he left on February 28, Benedict told those who greeted him at Castel Gandolfo was now a "a simple pilgrim" in the last stage of his earthly journey, but that he was not leaving the Church and would remain with it in spirit and prayer.

On his final day in the papacy Benedict stressed he would leave his jobs pledging his "unconditional reverence and obedience" to his successor who had not yet been chosed. He repeated his committment when Francis joined him for lunch on March 23.

The retired pope's residence  has a small library and a study along with a guest room where he will continue to wear his white papal cassock.