That Eusebius afterwards delivered his Description of the Church of the Saviour, and a Tricennial Oration before Constantine himself
The structure of the church of our Saviour, the form of his sacred cave, the splendor of the work itself, and the numberless offerings in gold, and silver, and precious stones, I have described to the best of my ability, and dedicated to the emperor in a separate treatise, which on a fitting opportunity I shall append to this present work. I shall add to it also that oration on his Tricennalia which shortly afterwards, having traveled to the city which bears his name, I delivered in the emperor's own presence. This was the second opportunity afforded me of glorifying the Supreme God in the imperial palace itself: and on this occasion my pious hearer evinced the greatest joy, as he afterwards testified, when he entertained the bishops then present, and loaded them with distinctions of every kind.
Source: Life of Constantine (New Advent)