The Vatican has announced Pope Emeritus Benedict XVI will take part in the official inauguration of the Jubilee of Mercy with the opening of the Holy Door on Dec. 8.

The retired pontiff “accepted the invitation of Pope Francis to attend the opening of the Holy Door” in St. Peter’s Basilica, Holy See press office director, Fr. Federico Lombardi, SJ. said Dec. 5.

He added that Benedict XVI would not take part in the whole ceremony, but said he would be “present in the Basilica Atrium on the occasion of the right of opening,” following the Eucharistic celebration.

This will be the first time the Holy Door has been opened since the Great Jubilee in the 2000 called for by St. John Paul II.

Tuesday’s celebrations will also mark one of Benedict XVI’s rare public appearances since his retirement in 2013. Since then, the emeritus pontiff has taken part in a few events at the invitation of Pope Francis including the consistory in Feb. 22, 2014; the festival of grandparents Sept. 27, 2014; and the Canonization Mass of John XXIII and John Paul II on Apr. 27, 2014.

The rite of the opening of the Holy Door is intended to symbolically illustrate the idea that the Church’s faithful are offered an “extraordinary path” toward salvation during the time of jubilee.

Each of the four major basilicas in Rome has a holy door, which are normally sealed shut from the inside so that they cannot be opened. The doors are only opened during jubilee years so that pilgrims can enter through them in order to gain the plenary indulgence that is connected with the jubilee.

Holy Doors in Rome’s other major basilica’s will be opened throughout the Jubilee year. St. John Lateran’s door will open Dec. 13, St. Mary Major’s Jan. 1, 2016, and St. Paul Outside the Walls will open Jan. 26, 2016.

One of the novelties for the upcoming Jubilee of Mercy is that for the first time Holy Doors will be designated in every diocese throughout the world.

For the first time Holy Doors will be designated in dioceses, and will be located either in the cathedral, in a church of special significance or a shrine of particular importance for pilgrimages.

The Jubilee of Mercy is an Extraordinary Holy Year that will open this year on Dec. 8 — the Solemnity of the Immaculate Conception — and will close Nov. 20, 2016 with the Solemnity of Christ the King.

The Pope first announced the Year of Mercy on March 13, the second anniversary of his pontifical election, during a Lenten penitential liturgy in St. Peter’s Basilica.

On April 11, the Holy Father officially proclaimed the Jubilee Year with the release of the Bull of Indiction.

Mercy is a theme that is dear to Pope Francis, and is the central topic of his episcopal motto “miserando atque eligendo,” which he chose when ordained a bishop in 1992.