Cardinal Walter Kasper, 78, a native of Germany, will represent the Pope at the event on Sunday.

The Holy Father's Latin-language letter appointing the cardinal was released today.

The papal letter notes the significance of the cathedral, which was built between 1030 and 1061, underlining its role in confirming the faith of the German people and their union with Peter's Successor.

The Pontiff invited the faithful to practice the Christian virtues of faith, hope and charity, like the Virgin Mary to whom the cathedral is dedicated.