the Stations of the Cross, came from just that, stations in Jerusalem where churches were built on the sites where each of the events of the Passion happened. The memory of these sites and events was preserved through Sacred Tradition, and as soon the Church was safe from persecution churches were built at each site, largely through the instigation of Helen, mother of Constantine, who made it her business to document these things. The pious custom grew of a pilgrimage to a Jerusalem, and walking to each site to pray in the churches.
After the Crusaders were finally driven out of Jerusalem and it was no longer possible to make this pilgrimage, St Francis, who himself had courageously visited the Muslim leader, came up with the idea of erecting stations, either pictures or sculptures, in parish churches so people could make the same devotional pilgrimage. While not every incident is described completely in the gospels, they all have scriptural roots, and in any case were part of the continuous recollection of the Church that survives in Tradition.
