That he instructed the Governors concerning the Beautifying of the Roof; also concerning Workmen, and Materials
“With respect to the ceiling of the church, I wish to know from you whether in your judgment it should be panel-ceiled, or finished with any other kind of workmanship. If the panel ceiling be adopted, it may also be ornamented with gold. For the rest, your Holiness will give information as early as possible to the before-mentioned magistrates how many laborers and artificers, and what expenditure of money is required. You will also be careful to send us a report without delay, not only respecting the marbles and columns, but the paneled ceiling also, should this appear to you to be the most beautiful form. God preserve you, beloved brother!”
Source: Life of Constantine (New Advent)