As Monsignor P. E. Hallett explains in his study on canonization, the Church constantly “had to guard against the extravagant and unauthorized devotion of the people.” Indeed, Charlemagne himself was the author of a synodal law designed to check the arbitrary veneration of alleged saints. read more
) years ago, but she's had shrines etc. since the twelfth century. But any of the big saints would certainly fit this mold. St. Martin of Tours died in 397, and he preceded the existence of papal canonization by a millennium; churches and abbeys to him still dot much of Europe. read more