Madain Saleh is the southernmost outpost of the Nabateans; these
    tombs are from the first century, CE.  KAUST arranged this CAVEcam
    expedition as part of a training session conducted by Dick
    Ainsworth, Tom DeFanti, and Dan Sandin, for KAUST Visualization
    Lab team members.  This image shows a tomb in the distance carved
    from the sandstone, and a good idea of the native cliffs.