the solemnity of Mary, Mother of God
Sts. Peter & Paul
However, depending on what country you live in, some bishops' Conferences have requested to be released from some Holy Days of Obligation (they are still Holy Days, but, for instance, in the United States, you are not obligated to go to Mass on St. Joseph's, Sts. Peter & Paul, or Corpus Christi under pain of sin. Other days may be transferred to the nearest Sunday. Some bishops' conferences release their subjects from the Obligation if some Holy Days fall on a Saturday or Monday.