In the 1st century A.D. the Roman Imperial authorities began to exploit the gold deposits of this region in north-west Spain, using a technique based on the utilization of hydraulic power. After two centuries of working the deposits, the Romans withdrew, leaving a devastated landscape. Since there was no subsequent industrial activity, the dramatic traces of this remarkable ancient technology are everywhere visible, in the form of sheer faces in the mountainsides and vast areas of tailings, now in use for agriculture.