When did Saint Ursula die?

A.d. 453
Good question. Actually, Ursula is a saint of legend and may have never exisited as there is little evidence to confirm her life. She was removed from the Universal Calendar of Saints in 1969. A legend resembling the life of Ursual seems to have developed in the 8th and 9th centuries.
453 AD

Her Memorial Day is on October 21st