Library Eusebius of Caesarea Life of Constantine
Book 3, Chapter 34: Description of the Structure of the Holy Sepulchre.
This monument, therefore, first of all, as the chief part of the whole, the emperor's zealous magnificence beautified with rare columns, and profusely enriched with the most splendid decorations of every kind.
English translation by Ernest Cushing Richardson, in Nicene and Post-Nicene Fathers, Series II, Vol. I (eds. Philip Schaff and Henry Wace; Buffalo: Christian Literature Publishing Co., 1890). Public domain. Digital text via New Advent Church Fathers.