igging on a coastal plain at the Gulf of Corinth three years ago, archaeologists came upon some ruins of Helike, a Greek city destroyed by earthquake in Plato's time. A search for the rest of Helike has now turned up something even more ancient, rare and inviting.The archaeologists say they have uncovered the stone foundations, cobbled streets and pottery of a well-preserved 4,500-year-old urban center, one of the few Early Bronze Age communities ever found on the Greek mainland.Preliminary investigation at the prehistoric site, the researchers say, reveals that this was a prosperous town at the time pre-Homeric Troy enjoyed...