What does not appear to be generally known, even among historians of chemistry, is that some evidence exists for the use of a uranium mineral or compound by the Romans in Italy soon after the beginning of the Christian era. While excavating the Imperial Roman Villa on Cape Posilipo on the shore of Naples Bay a remarkable glass mosaic mural was discovered. Analysis of a specimen of a pale green glass was made. It was decided that a substance in the glass was uranium oxide. Later study indicated that this may have been uranium dioxide or possibly uranosic oxide. The mural was dated at 79 A.D. In the light of our present knowledge of the composition of ancient materials, this date may then be taken as fixing the approximate time of the first use of uranium glass and the approximate time of the first use of any kind of material containing uranium.