According to tradition, Mary first walked the Way of the Cross on Holy Saturday after Jesus was crucified, then continued to visit the places of His suffering, death, and resurrection, and later Mary, the disciples, and the holy women followed that path in prayer and remembrance. Early Christian pilgrims traveled to Jerusalem to walk in Christ's footsteps on the road to Calvary, and so many came that Emperor Hadrian built a pagan temple on Mount Calvary to keep them away. After persecution ended in 313 under Emperor Constantine, pilgrims could legally worship in the Roman Empire and return freely to Jerusalem. In 325 Saint Helena found the true Cross on Calvary and had a church built where Hadrian's temple had stood, and in 335 Constantine erected the Church of the Holy Sepulcher at the site believed to be Jesus's tomb, helping make Jerusalem the greatest pilgrimage site in the world. As devotion spread, Christians sought to reproduce Jerusalem's holy places elsewhere, including connected chapels at the monastery of San Stefano at Bologne built by Saint Petronius, Bishop of Bologna, which may mark the beginning of the Stations of the Cross. After the Crusades and the fall of the Holy Land to the Turks made pilgrimage dangerous and difficult, many Christians turned instead to meditation on the Stations of the Cross, often aided by visual representations of the Passion. The Franciscans, granted custody of Christian sites in Jerusalem in 1842, promoted this devotion in Europe as a spiritual substitute for pilgrimage, and it soon spread worldwide. The term "Stations" appears in the account of the English pilgrim William Wey, who visited the Holy Land in 1458 and 1462, and over time the practice developed through varying numbers of stations in manuals, manuscripts, and books before the present form emerged. Important steps included Peter Sterckx's 1595 Way of the Cross of Louvain with 8 stations, reports in 1515 that there should be 31, the 1550 manuscript of Saint-Trond with 12 episodes, John Pascha's 1563 Spiritual Pilgrimage, the 1435 account by Hans Lochner adding Veronica and the daughters of Jerusalem, and Adrichomius's 1584 reconstruction giving 12 stations that match the first 12 used today. In the sixteenth century, devotional manuals in the Low Countries introduced some of the 14 stations now used. In 1686 Pope Innocent XI allowed stations in all Franciscan churches, in 1691 Pope Clement XII allowed them in all churches and confirmed the number at 14, and Saint Leonard of Port Maurice formalized the 14 Stations of the Cross and erected more than 570 sets between 1731 and 1751. Pope Benedict XIV urged every church in 1742 to enrich its sanctuary with stations, and in 1787 Saint Alphonsus Ligouri wrote the version most Americans came to know, widely used in the United States during the nineteenth and twentieth centuries. Throughout, the devotion has centered on remembering Christ's passion, death, and resurrection and on spiritually following Him by taking up the cross.