Ephesus is the most impressive ancient site accessible from İzmir and one of the best-preserved Roman cities in the world. At its peak in the second century CE, Ephesus had a population of around 250,000 — comparable to Rome itself — and the excavated remains give a genuine sense of that scale: marble-paved streets, a library facade 17 metres tall, a theatre seating 24,000 people.
From İzmir, take the train to Selçuk (about 75 minutes, several departures daily) and then a taxi or dolmuş to the site. Allow at least four hours on site, and start early — the heat and the crowds both build quickly after 10am. The terrace houses, requiring a separate ticket, are among the finest examples of Roman domestic painting outside Pompeii.