The Solemnity of Sts. Peter and Paul, Apostles and Martyrs
is today. There is information on them here and here.

Too many persons at this day,—in spite of what they see before them, in spite of what they read in history,—too many persons forget, or deny, or do not know, that Christ has set up a kingdom in the world. In spite of the prophecies, in spite of the Gospels and Epistles, in spite of their eyes and their ears,—whether it be their sin or their misfortune, so it is,—they do not obey Him in that way in which it is His will that He should be obeyed. They do not obey Him in His Kingdom; they think to be His people, without being His subjects. They determine to serve Him in their own way; and though He has formed His chosen into one body, they think to separate from that body, yet to remain in the number of the chosen.

Far different is the doctrine suggested to us by the text. In St. Peter, who is there made the rock on which the Church is founded, we see, as in a type, its unity, stability, and permanence. It is set up in one name, not in many, to show that it is one; and that name is Peter, to show that it will last, or, as the Divine Speaker proceeds, that "the gates of hell shall not prevail against it." In like manner, St. Paul calls it "the pillar and ground of the truth." [1 Tim. iii. 15.]

Venerable John Henry Newman, Parochial and Plain Sermons