Pope Benedict is retiring from his duties.
People around the world are marking the event with special ceremonies, including in Sioux Falls where a Mass of Thanksgiving was held over the noon hour at St. Joseph Cathedral.
The pope is set to become the first pontiff in 600 years to resign. Late Thursday morning, he left the castle and boarded a helicopter to go to a retreat.
On Monday, cardinals are expected to begin meeting to set the date for the conclave to select a new pope.