Also, here is an account from the ancient historian, Eusebius, about how St. Constantine, Emperor of the Eastern Roman Empire, built the Church in the 4th century AD with the help of his devout mother, St. Helena:
Chapter XXV.--How he ordered the Erection of a Church at
“After these things, the pious emperor addressed himself to another work truly worthy of record, in the
Chapter XXVI.--That the Holy Sepulchre had been covered with Rubbish and with Idols by the Ungodly.
“For it had been in time past the endeavor of impious men (or rather let me say of the whole race of evil spirits through their means), to consign to the darkness of oblivion that divine monument of immortality to which the radiant angel had descended from heaven, and rolled away the stone for those who still had stony hearts, and who supposed that the living One still lay among the dead; and had declared glad tidings to the women also, and removed their stony-hearted unbelief by the conviction that he whom they sought was alive. This sacred cave, then, certain impious and godless persons had thought to remove entirely from the eyes of men, supposing in their folly that thus they should be able effectually to obscure the truth. Accordingly they brought a quantity of earth from a distance with much labor, and covered the entire spot; then, having raised this to a moderate height, they paved it with stone, concealing the holy cave beneath this massive mound. Then, as though their purpose had been effectually accomplished, they prepare on this foundation a truly dreadful sepulchre of souls, by building a gloomy shrine of lifeless idols to the impure spirit whom they call Venus, and offering detestable oblations therein on profane and accursed altars. For they supposed that their object could not otherwise be fully attained, than by thus burying the sacred cave beneath these foul pollutions.”
“Nor did the emperor's zeal stop here; but he gave further orders that the materials of what was thus destroyed, both stone and timber, should be removed and thrown as far from the spot as possible; and this command also was speedily executed. The emperor, however, was not satisfied with having proceeded thus far: once more, fired with holy ardor, he directed that the ground itself should be dug up to a considerable depth, and the soil which had been polluted by the foul impurities of demon worship transported to a far distant place.”
"Victor Constantius, Maximus Augustus, to Macarius.
"Such is our Saviour's grace, that no power of language seems adequate to describe the wondrous circumstance to which I am about to refer. For, that the monument of his most holy Passion, so long ago buried beneath the ground, should have remained unknown for so long a series of years, until its reappearance to his servants now set free through the removal of him  who was the common enemy of all, is a fact which truly surpasses all admiration. For if all who are accounted wise throughout the world were to unite in their endeavors to say somewhat worthy of this event, they would be unable to attain their object in the smallest degree. Indeed, the nature of this miracle as far transcends the capacity of human reason as heavenly things are superior to human affairs. For this cause it is ever my first, and indeed my only object, that, as the authority of the truth is evincing itself daily by fresh wonders, so our souls may all become more zealous, with all sobriety and earnest unanimity, for the honor of the Divine law. I desire, therefore, especially, that you should be persuaded of that which I suppose is evident to all beside, namely, that I have no greater care than how I may best adorn with a splendid structure that sacred spot, which, under Divine direction, I have disencumbered as it were of the heavy weight of foul idol worship; a spot which has been accounted holy from the beginning in God's judgment, but which now appears holier still, since it has brought to light a clear assurance of our Saviour's passion.
Chapter XXXI.--That the Building should surpass all the Churches in the World in the Beauty of its Walls, its Columns, and Marbles.
"It will be well, therefore, for your sagacity to make such arrangements and provision of all things needful for the work, that not only the church itself as a whole may surpass all others whatsoever in beauty, but that the details of the building may be of such a kind that the fairest structures in any city of the empire may be excelled by this. And with respect to the erection and decoration of the walls, this is to inform you that our friend Dracilianus, the deputy of the Praetorian Praefects, and the governor of the province, have received a charge from us. For our pious directions to them are to the effect that artificers and laborers, and whatever they shall understand from your sagacity to be needful for the advancement of the work, shall forthwith be furnished by their care. And as to the columns and marbles, whatever you shall judge, after actual inspection of the plan, to be especially precious and serviceable, be diligent to send information to us in writing, in order that whatever quantity or sort of materials we shall esteem from your letter to be needful, may be procured from every quarter, as required, for it is fitting that the most marvelous place in the world should be worthily decorated.”
Chapter XXXII.--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!"
Chapter XXXIII.--How the Church of our Saviour, the New Jerusalem prophesied of in Scripture, was built.
“This was the emperor's letter; and his directions were at once carried into effect. Accordingly, on the very spot which witnessed the Saviour's sufferings, a new Jerusalem was constructed, over against the one so celebrated of old, which, since the foul stain of guilt brought on it by the murder of the Lord, had experienced the last extremity of desolation, the effect of Divine judgment on its impious people. It was
opposite this city that the emperor now began to rear a monument to the Saviour's victory over death, with rich and lavish magnificence. And it may be that this was that second and new
First of all, then, he adorned the sacred cave itself, as the chief part of the whole work, and the hallowed monument at which the angel radiant with light had once declared to all that regeneration which was first manifested in the Saviour's person.”
Chapter XLII.--That the Empress Helena, 
“For she, having resolved to discharge the duties of pious devotion to the God, the King of kings, and feeling it incumbent on her to render thanksgivings with prayers on behalf both of her own son, now so mighty an emperor, and of his sons, her own grandchildren, the divinely favored Caesars, though now advanced in years, yet gifted with no common degree of wisdom, had hastened with youthful alacrity to survey this venerable land; and at the same time to visit the eastern provinces, cities, and people, with a truly imperial solicitude. As soon, then, as she had rendered due reverence to the ground which the Saviour's feet had trodden, according to the prophetic word which says  "Let us worship at the place whereon his feet have stood," she immediately bequeathed the fruit of her piety to future generations.”
Eusebius, “The Life of
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