Ephesus is one of the largest and best-preserved ancient cities in the Mediterranean world, located near the town of Selçuk on Turkey's Aegean coast. At its height in the Roman imperial period it had a population of perhaps 200,000 people and was the most important city in the Roman province of Asia — wealthier, larger, and more culturally significant than most cities anywhere in the ancient world. Its ruins cover several square kilometres and include a theatre that seated 25,000, the iconic two-storey facade of the Library of Celsus, marble-paved streets, public latrines, gymnasia, and the Terrace Houses where Roman domestic spaces survive with mosaics and frescoed walls still intact.
The city's history goes back at least to the 10th century BC. It was Lydian, then Persian, then Hellenistic, then Roman. The Temple of Artemis that stood here — one of the Seven Wonders of the Ancient World — was in its final form larger than the Parthenon. The Apostle Paul preached here and was briefly imprisoned, and the city appears repeatedly in early Christian history: the Church of Mary, at the northern edge of the site, hosted the Third Ecumenical Council of 431 which declared Mary to be the Mother of God. When the harbour silted up over centuries and the sea retreated, the city gradually lost its commercial reason to exist. Today the ancient site is about 5 km from the coast, stranded inland by the same alluvial processes that eventually killed it.
The walk up Curetes Street — the marble-paved main street lined with the bases of statues, the Temple of Hadrian, the public latrines, and the enormous Great Theatre looking down the processional way to the vanished harbour — is one of the great walks in the ancient world. Start early, allow a full day, and visit the Ephesus Archaeological Museum in Selçuk for the finds. The Basilica of Saint John and the İsa Bey Mosque are also in Selçuk and round out the visit.