Who were the Celts? They grew rich in 'Salt-City,' the great rock-salt deposits near Salzburg in Austria. They were famous throughout the Roman world for their thirst for wine, their lust for human sacrifice and their astronomer druids. They rode moustachioed and naked into battle in chariots and their art was one of the great achievements of prehistoric Europe. David Parry-Jones describes the archaeologists' search for a culture which ranges across 28 centuries, and from Anatolia to Ireland, and is often as mysterious and ambiguous as its art.