Empress Helena ( c. 250 â `` c. 330 AD ) was the mother of Constantine , the first Christian Emperor of Rome . According to post-Nicene historians , Socrates Scholasticus and others , the Empress Helena ( c. AD 250 â `` c. AD 330 ) , mother of Constantine , the first Christian Emperor of Rome , traveled to the Holy Land , dated by modern historians in 326-28 , founding churches and establishing relief agencies for the poor .