Being a Vestal Virgin was a lifetime committment that required certain promises be made to the powerful position. Breaking a promise made in honor of the priesthood spelled certain disaster. For example, breaking the vow of celibacy usually meant execution for the former Virgin. Over the course of Roman history, the technique of execution that was employed varied. The final punishments inflicted upon the offending priestesses included (and were probably not limited to) being buried alive, being thrown into the Tiber River, and being publicly whipped. It was a strong incentive for a Virgin to keep her tunic down. Additionally, and most importantly, if a Vestal Virgin let the ceremonial fire at the Temple of Vesta burn out, she was also punished by execution.
As mentioned before, the Vestal Virgins played a vital role in the Vestalia, the annual ritual in honor of their patron goddess, Vesta. The celebration took place every June 7 - 15. On the first day of the Vestalia, the doors of the Temple of Vesta opened to the mothers of the families of Rome who brought offerings of food to the goddess. The Virgins also prepared special food offerings at this time. This occasion was the only time of year that the doors of the temple were opened to the public.
The Vestal Virgins, through their social and personal sacrifices, were afforded many benefits traditionally permitted only to Roman men. The price at which these benefits came was potentially steep: execution. But if they did their job well and without flaw, the reverence these women felt must have been intoxicating, perhaps empowering. Roman women were afforded very few opportunities to be in positions of power and respect. And though the concept of the Vestal Virgin might seem degrading and antediluvian to us today, this role in Roman life and religion was so very vital and respected by all Roman citizens.
As the prevalence of Christianity began to wash over the Roman Empire, it was only natural that the Emperors would eventually begin to adopt this new way of life. The College of the Vestal Virgins was disbanded in 394 AD and the ceremonial fire was extinguished by Emperor Theodosius I (the Emperor was known at this point in Roman History as "Pontifex Maximus"). Theodosius was a Christian Emperor, and with this transition, many of the old Pagan customs were eradicated, including the Vestal Virgins. However, it is interesting to note that the Catholic Church clearly saw some benefit in retaining certain aspects of pagan religious customs as a means of making this still new religion attractive to new converts. They adopted many of the old ideas into the new tenets. For example, the College of the Vestals seems to have evolved into the concept of convents and nuns being governed by the Pontifex Maximus (the Pope).