Earlier, Benedict met the German Chancellor, Gerhard Schröder, and his election challenger, Angela Merkel, before a meeting with Muslim leaders from Germany's Turkish community.
Organisers said about 200,000 people were already in place under cloudy skies by mid-afternoon for the vigil service. They staked out places on the grass to sleep in the open so they can attend today's concluding mass to be celebrated by the Pope. Some 400,000 pilgrims have arrived in Cologne for the festival during the week, and organisers say the crowd at the concluding mass in the Marienfeld, or Mary's Field, could be 800,000 or more.
Ms Merkel, leader of the Christian Democratic Union and the daughter of a Protestant minister, said after her meeting with the Pope that "it was a great joy to see the Holy Father. It was great to meet a German Pope on German soil."
Chancellor Schröder, who is also Protestant, as are about one-third of Germans, had no immediate comment on his discussions with the pontiff.
Young people have given Benedict an enthusiastic reception at the festival, which was founded by his predecessor, John Paul II, as a way to evangelise young people. He has made a more subdued impression than the charismatic John Paul, reading his speeches in a soft voice and not kissing the ground on arrival. Nonetheless, people have cheered wildly and shouted his name at every appearance.
The Pope's evening meeting with Muslims will be the second major test of interfaith relations during Benedict's four-day homecoming trip, his first foreign journey since his April election.
It follows Friday's visit to Cologne's synagogue, where Benedict was warmly received by Jewish officials for his remarks urging better Jewish-Christian relations and warning of rising anti-Semitism. (AP)Reuse content