SOLEMN PONTIFICAL MASS in the Ambrosian Rite celebrated by Cardinal Montini—later elected Pope Paul VI—in the St. Peter’s Basilica during the Second Vatican Council:

Courtesy of this wonderful Polish blog.
Pope Saint Paul VI (3 April 1969): “Although the text of the Roman Gradual—at least that which concerns the singing—has not been changed, the Entrance antiphons and Communions antiphons have been revised for Masses without singing.”