On a golden day last September, I visited the ruins of the first Greek city on the Iberian Peninsula, a settlement from the sixth century B.C. called Empúries. Traders venturing down present-day Spain’s Costa Brava, a rugged stretch of coastline in northeastern Catalonia, had recognized the advantages of the location: a natural port, some protection from the fierce tramontana winds blowing off the Pyrenees, and access to local trade networks established by native Iberians. But as the Greek settlers discovered, another attribute of their new home lay just offshore.
