OPE SAINT JOHN XXIII was famous for visiting prisons—and YouTube has several fascinating videos documenting his custom—but until I stumbled across the following film, I never knew that he brought an Altar into the prison for Benediction:
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.”