Legend says that Celtic Christianity in Britain was founded by St. Joseph of Arimathea; legend also says that King Arthur is buried in his ruined abbey. According to legend, Joseph was a tin merchant who was often coming and going to the tin mines of Roman Britain. Legend continues to say that he may have taken his nephew, Jesus, with him on some of these trips. Later Joseph of Aramathea becomes first keeper of the Holy Grail. Perhaps the best known myth about Celtic Christianity is that Saint Patrick brought Christianity to Ireland. Christianity was already established in Ireland by the time Patrick began his ministry. 