The case for visiting Kuşadası is that it is the best base for one of the densest classical archaeological landscapes in the world. Most visitors organise their stay around day trips inland and along the coast.
Ephesus, half an hour north past Selçuk, is the headline trip — one of the largest and best-preserved Greco-Roman cities anywhere in the Mediterranean. The Library of Celsus, the Great Theatre, the Curetes Street, and the Terrace Houses on the slope are essential. Start early to beat both the heat and the cruise groups. Selçuk town itself has the Ephesus Museum, the basilica and tomb of St John, and the single surviving column of the Temple of Artemis (one of the Seven Wonders of the Ancient World).
Priene, Miletus, and Didyma to the south make a classic single-day loop. Priene is the small Greek city on a hillside, well preserved and rarely crowded; Miletus is much larger but ruined and partly swampy; Didyma is the spectacular oracle temple of Apollo with two intact columns still standing on top of an enormous stylobate. A driver and a long day will see all three.
Pamukkale and Hierapolis are three hours inland by car — the famous white travertine terraces of hot mineral water, and above them a sprawling Roman-Byzantine city. Worth the long day for the unique landscape.
House of the Virgin Mary (Meryem Ana Evi) sits in pine forest in the hills above Ephesus. Catholic tradition holds that Mary spent her last years here under the protection of the apostle John. The small stone chapel attracts pilgrims year-round.