The city is situated along a gulf of the same name in the Aegean, with the island of Güvercin Ada connected to the mainland by a narrow passage on one end, and the mountain of Kese Dağı behind.
It is located 95 km (59 mi) south of İzmir, the area's metropolitan centre, and 71 km (44 mi) from the provincial seat of Aydın. Its neighbours are Selçuk from north, Germencik from north-east and Söke from east and south.
Kuşadası has a residential population of 64,359, which can rise to over half a million in the summer as a result of the large resort filling with tourists. This also includes the hotel and bar staff, construction workers, and drivers who are required to work in/for the restaurants and other services accommodating these visitors. In addition to tourists from overseas, there is also a significant community of foreigners residing in the area.
The name comes from 'kuş' (bird) and 'ada' (island), as the island has the shape of a bird's head (as seen from the sea). It was known as Ephesus Neopolis, in Greek (Ἔφεσος Νεόπολις), during the Byzantine era, and later as Scala Nova or Thataub under the Genovese and Venetians. Kuş Adası was adopted in its place at the beginning of the 20th century. Today, citizens of Kuşadası often shorten the name to Ada.
The area has been a centre of art and culture since some of the earliest recorded history, and has been settled by many civilizations since being founded by the Leleges people in 3000 BC. Later settlers include the Aeolians in the 11th century BC and Ionians in the 9th. Originally, seamen and traders built a number of settlements along the coastline, including Neopolis.
An outpost of Ephesus in ancient Ionia, known as Pygela (Πύγελα), the area between the Büyük Menderes (Maeander) and Gediz (Hermos) rivers, the original Neopolis, is thought to have been founded on the nearby point of Yılancı Burnu. Later settlements were probably built on the hillside of Pilavtepe, in the district called Andızkulesi today. Kuşadası was a minor port frequented by vessels trading along the Aegean coast. In antiquity it was overshadowed by Ephesus, until Ephesus' harbor silted up. From the 7th century BC onwards the coast was ruled by Lydians from their capital at Sardis, then from 546 BC the Persians, and from 334 BC, along with all of Anatolia, the coast was conquered by Alexander the Great. From that point on the coastal cities in Anatolia became a centre of Hellenistic culture.