Pope Emeritus Benedict XVI will be present at an encounter with Pope Francis and the elderly on Sunday morning in St. Peter's Square, the Vatican announced Friday.

According to a Sept. 26 satement from the Holy See press office on, the encounter will precede a Mass said for grandparents and the elderly which will be said at 10:30 am.

Benedict XVI, who is 87, will depart prior to the beginning of Mass.

Some 40,000 seniors from more than 20 countries are expected to participate in the Mass. Included in this number are  persons from Italy, Spain, Argentina, and the United States.

The Pontifical Council for the Family said that more than 50 elderly priests will concelebrate the Mass with Pope Francis, including the oldest priest of the Diocese of Rome, as well as priests from the Democratic Republic of Congo, India, and Argentina.