13.8 343 Vatican City, excavations under St. Peter’s, Mausoleum F, stuccoes 13.9 346 Vatican City, excavations under St. Peter’s, Campo P, plan 13.10 348 Vatican City, excavations under St. Peter’s, Aedicula, reconstruction 1 Prehistoric Italy In May of 1945 two young British Army officers, John Bradford and Peter Williams-Hunt, based with the R.A.F. at Foggia in the province of Puglia, near the heel of Italy, found that the World War II armistice left them with time on their hands. Both trained archaeologists, they readily prevailed upon the R.A.F. to combine routine training flights with pushing back the frontiers of science. The result of their air reconnaissance was to change profoundly the archaeological map of Italy. The value of air-photography for archaeology had long been known; as early as 1909 pictures taken from a balloon had revealed the plan of Ostia, the port of ancient Rome. But the English, especially such pioneers as Major G. W. G. Allen and O. G. S. Crawford, early took the lead in interpreting, on photographs taken usually for military purposes, vegetation-marks showing the presence and plan of ancient sites buried beneath the soil, and invisible to the groundling’s eye. Where the subsoil has been disturbed in antiquity by the digging of a ditch, the increased depth of soil will produce more luxuriant crops or weeds; where soil-depth is decreased by the presence of ancient foundations, walls, floors, or roads, the crop will be thin, stunted, lighter in color. Air-photographs taken in raking light, just after sunrise or just before sunset in a dry season, especially over grassland, will highlight these buried landscapes. The Tavoliere, the great prairie where Foggia lies, thirty by fifty-five miles in extent, suits these conditions admirably; its mean annual rainfall is only 18.6 inches (0.6 in July) or half that of Rome, and Rome is a dry place, at least in summer. So Bradford and Williams-Hunt had high hopes for their project. In a Fairchild high-wing monoplane, in which the position of struts and nacelles does not interfere with the operation of a hand-held camera, they took oblique shots at 1,000 feet with an air camera of 8-inch focal length. For vertical shots they used, at 10,000 feet, air cameras of 20-inch focal length, mounted tandem to produce overlap for stereoscopic examination, which makes pictures three-dimensional. The thousands of resulting photographs were at a scale of about 1:6000, or ten inches to the mile, over four times as large as the best available ground maps (the 1:25,000 series of the Italian Istituto Geografico Militare.)