Opus id fecisse dicuntur CXX hominum. ipse rex, cum surrecturus esset verereturque, ne machinae ponderi non sufficerent, quo maius periculum curae artificum denuntiaret, filium suum adalligavit cacumini, ut salus eius apud molientes prodesset et lapidi. hac admiratione operis effectum est, ut, cum oppidum id expugnaret Cambyses rex ventumque esset incendiis ad crepidines obelisci, extingui iuberet molis reverentia qui nullam habuerat urbis.
(Pliny the Elder, Nat. Hist. 36.66)
It is said that one hundred and twenty thousand men were employed upon this work;* and that the king, when it was on the point of being elevated, being apprehensive that the machinery employed might not prove strong enough for the weight, with the view of increasing the peril that might be entailed by due want of precaution on the part of the workmen, had his own son fastened to the summit; in order that the safety of the prince might at the same time ensure the safety of the mass of stone. It was in his admiration of this work, that, when King Cambyses took the city by storm, and the conflagration had already reached the very foot of the obelisk, he ordered the fire to be extinguished; he entertaining a respect for this stupendous erection which he had not entertained for the city itself.
* This, Hardouin says, was the same obelisk that was afterwards erected by Constantius, son of Constantine the Great, in the Circus Maximus at Rome; whence it was removed by Pope Sextus V., in the year 1588, to the Basilica of the Lateran.
(tr. John Bostock & H.T. Riley, with their note)