How did Leo X support the construction of St. Peter’s Basilica?

Pope Leo X supported the construction of St. Peter’s Basilica by accelerating the project initiated by his predecessor, Pope Julius II. To fund this and other financial obligations, Leo X reaffirmed the use of indulgences—the remission of temporal penalties for sin—which allowed the faithful to make financial contributions toward the basilica's construction.123

While indulgences had been authorized for this purpose under Julius II, Leo X’s continued reliance on them to raise revenue became a significant point of contention. The preaching of these indulgences by the Dominican friar Johann Tetzel in Germany eventually prompted Martin Luther to circulate his Ninety-five Theses in 1517, challenging the practice. Although the sale of indulgences was intended to finance the church, it is important to note that a portion of the proceeds in Germany was diverted to pay off debts incurred by the archbishop of Mainz, a fact that fueled further public criticism of the papacy's methods.23