They entered the service of the goddess at from six to ten years of age, their term of service lasting thirty years. They were then permitted to retire and to marry, but few did so, for, as vestals, they were treated with great honor, and had important public privileges. Their persons were inviolable, any offense against them being punished with death, and they were treated in all their relations with the highest distinction and reverence. A vestal who broke her vow of chastity was immured alive in an underground vault amid public mourning. There were very few such instances; in one of them, under Domitian, the chief of the vestals was put to death under a false charge trumped up by the emperor. [Century Dictionary]