What is Saint Helen known mostly by?

I am not sure if I understand your question. However, I will answer what I think you are asking.

St. Helena was the mother of Roman Emperor Constantine the Great. When she was 80 years old she led a pilgrimage to the Holy Land to search for the True Cross on which Our Lord was crucified. She found what is believed to be the cross as well as a number of other important relics and sites that were part of Our Lord's life and passion. With the help of her son, she also constructed a number of shrines and churches in the Holy Land over or near these important sites.