The obelisks of Rome were souvenirs of the Empire’s conquest of Egypt, and most of them had been brought to the city in imperial times. Ancient Egypt had three basic commemorative forms: the pyramid, the sphinx, and the obelisk. But the task of moving an obelisk (never mind a sphinx or a pyramid) across the Mediterranean was hardly less daunting than making the thing to begin with, which was difficult enough—indeed, insanely so—and could only have been undertaken by a theocratic anti-state like ancient Egypt.
All known Egyptian obelisks came from the same quarry—a deposit of extremely hard and fine-grained syenite, a rock similar to granite, at Aswan, below the first cataract of the Nile. It lay seven hundred miles from Alexandria and five hundred from Heliopolis, where the biggest concentration of finished obelisks stood.
The tools of ancient Egypt were very simple. No stonecutting saws or explosives, of course; no steel; and for moving the heavy blocks of syenite, once they were free of the quarry, only the timber lever, the roller, the inclined plane, the wedge, palm-fiber ropes, grease, and limitless manpower. Human muscle, at least, was not in short supply, and it was preferred to animal traction, since the fellahin could obey orders a team of oxen would not understand. Egypt had about 11,500 square miles of inhabitable terrain, and a population, in pharaonic times, of perhaps eight million people, a density of some seven hundred per square mile—six times more than China’s or India’s then.
The task of cutting out the granite block for an obelisk was simplicity itself—tedious, infinitely laborious simplicity.
You and other slaves marked the intended line of cleavage in the granite by gouging a channel for its full length, about two inches deep and two wide. Into the bottom of this channel you drilled a line of holes, each about three inches in diameter and six inches deep, spaced some eighteen inches apart.
You and your fellow slaves now had two choices.
The first was to hammer a wooden plug into each of these holes and then fill the channel with water, which other slaves would have brought in skins from the nearby Nile. If, despite the evaporative power of the Egyptian sun, the wood was kept soaked long enough, the plugs would swell and, with luck, cause the whole mass to crack away from its matrix.
The second choice was to build a fire the whole length of the channel and keep it burning until the rock was piping hot, then sweep away the ash and embers and quickly douse it all with cold water, which (with luck) would also crack the granite.
No tools for work on the obelisks have ever been found, except a single bronze chisel at Thebes. Iron tools, if they existed at all, have entirely disappeared, rusted away (some think) by the highly nitrous Egyptian soil. Possibly the chisels had diamond teeth. For the long and arduous task of smoothing the faces of the obelisks, there must have been abrasives of some kind—emery, corundum, or even diamond dust. The main ingredient, of which ancient Egypt was never short, was limitless amounts of human labor.
How the obelisk got its final sculptural shape, with the “pyramidion” or point on top of the shaft, is not known. It cannot have been done with abrasives—there was too much rock to remove—but trying to split the waste rock off accurately at sixty degrees on all four faces must have been, to put it mildly, chancy.
Nevertheless, it was done, and now came the problem of getting the thing to its intended site. But this was not a matter to deter a really serious pharaoh. In the nineteenth dynasty, about 1400 B.C.E., Rameses II had a nine-hundred-ton effigy of himself dragged 138 miles from its granite bed to the memnorium in Thebes, on some kind of enormous sled, with obedient Egyptians pouring oil on the sand in front of its runners to reduce friction and thousands of other Egyptians hauling on ropes. The obelisk’s granite bed was not so far—at least, not unthinkably far—from the Nile. The best guess is that the Egyptians built a dry dock on the bank of the river, at low water. Inside this, a transport barge was constructed. Now the obelisk would be dragged from the quarry to the dry dock on a massive timber sledge, an operation requiring perhaps fifty thousand men in double or quadruple lines, and miles of palm-fiber rope.
Thus the obelisk would be loaded slowly, slowly into the barge, there to wait for the great event, the annual inundation of the Nile. This would raise the laden barge, which then, with great luck and skill, would be floated down the river to a place as close as possible to the obelisk’s appointed site. There, the patient Egyptians would run through the whole process again, this time backward, building another dry dock, securing the barge in it, waiting for the Nile water to recede, dragging the obelisk from the barge and the embankment to its eventual pedestal, and raising it vertical.
How this might have been done was entirely conjectural, and so it had to be reinvented again and again. First the ancient Romans, of the time of Cleopatra and Ptolemy, had to reinvent it, no doubt with a great deal of subservient Egyptian help. Then, more than a thousand years later, the Italians had to invent it once more, since there were no records of the original moves.
Of the ships that brought the obelisks to Rome, not a trace remains. It is presumed that they were enormous galleys, each custom-built, quinqueremes with at least three hundred oarsmen, and that the prone obelisk was ballasted with many tons of wheat or dried beans in sacks packed around it to prevent it from shifting, since any instability in so immense a load would have rolled the ship and sent it to the bottom at once. (Underwater archaeology has found an amazing variety of objects in ancient wrecks, including what some presume to have been a primitive ancestor of the computer off the island of Antikythera—the “Antikythera Mechanism”—but no obelisk so far.)
Once the ship and its cargo had reached Ostia, the entire process had to be repeated in reverse: the dry dock, the sledge, the hauling, and the inch-by-inch journey to Rome. Some obelisks, at least, were raised vertically on their bases in the Circus Maximus and elsewhere, but it is not known how. Most of them were broken into several pieces, either by toppling over in unrecorded antiquity, or by damage from earthquakes or ground subsidence as they lay prone.
There was, however, one perfect unbroken obelisk still standing in Rome in the sixteenth century. The largest intact one outside Egypt, it dated from the nineteenth dynasty, about 1300 B.C.E., and had been brought to the Eternal City on the orders of none other than Caligula, having been raised first at Heliopolis. Caligula decreed its transport to a site on Nero’s Circus, which, more than a thousand years later, turned out to be the back of the old Saint Peter’s Basilica. It was a tapering granite shaft, eighty-three feet and one inch to the tip of its pyramidion, weighing 361 tons. On top of the pyramidion was a bronze ball, which nobody had ever opened; it was reputed to contain the ashes of Julius Caesar.
Pope Sixtus V had often looked at the obelisk from afar, and was not satisfied. It should not be behind the new Basilica of Saint Peter’s, which was then nearing completion. It must be moved to the front. A simple matter of civic punctuation—shifting the exclamation point in the sentence. A great piazza would be made in front of the new Saint Peter’s (and so it was, years later, to the designs of the as yet unborn Gian Lorenzo Bernini). Let the obelisk be brought round and planted there, plumb in the center, to the wonder of pilgrims now, the edification of the faithful in centuries to come, and the eternal memory of Pope Sixtus V.