Benedict XVI has become the first pope in 600 years to resign, ending an eight-year pontificate shaped by struggles to move the church past sex abuse scandals and to reawaken Christianity in an indifferent world.

The Swiss Guards standing at attention in Castel Gandolfo shut the gates of the palazzo shortly after 8 p.m. Thursday (2 o'clock our time) symbolically closing the doors on a papacy whose legacy will be most marked by the way it ended, a resignation instead of a death.

In a final farewell to his cardinals as pope, Benedict tried to dispel concerns about the unprecedented future awaiting the Catholic
Church, with one reigning and one retired pope living side-by-side.

He pledged his ``unconditional reverence and obedience'' to his successor.