Our Gospel for this Sunday opens with Jesus' disciples admiring the splendor of the Temple, the most beautiful, important, and impressive building they had ever seen. And Jesus, as is his wont, pulls the rug out from under them: "Not one stone of this temple will be left upon another, but it will all be torn down!" The Gospel emphasizes over and again that nothing in this world lasts, nothing here below is ultimate. Therefore we shouldn't spend our time and energy gawking at the glories of this world; rather we should see and act in the light of a glory to come.
Bishop Barron’s Sunday Sermons - Catholic Preaching and Homilies