Miletus (Ancient Greek: Μίλητος, romanised: Mílētos) was an influential ancient Greek city on the western coast of Anatolia, near the mouth of the Maeander River in present day Turkey. Renowned in antiquity for its wealth, maritime power, and extensive network of colonies, Miletus was a major center of trade, culture, and innovation from the Bronze Age through the Roman period. The city played a foundational role in the development of early Greek philosophy and science, serving as the home of the Milesian school with thinkers such as Thales, Anaximander, and Anaximenes.

Miletus's prosperity was closely linked to its strategic coastal location and the productivity of its surrounding rural hinterland, which supported thriving agriculture and facilitated wide-ranging commercial activity. The city established dozens of colonies around the Mediterranean and Black Sea, significantly shaping the Greek world’s expansion.

Archaeological investigations have revealed a rich material culture, including the sanctuary of Apollo at Didyma, remnants of the city's distinctive grid plan, and evidence of long-term agricultural and rural management. Throughout its history, Miletus experienced periods of autonomy and foreign rule, serving as a cultural crossroads between Greek, Anatolian, and later Persian and Roman spheres. The city’s enduring legacy is reflected in its contributions to philosophy, urban planning, and the spread of Greek civilization.

The earliest available archaeological evidence indicates that the islands on which Miletus was originally placed were inhabited by a Neolithic population in 3500–3000 BC. Pollen in core samples from Lake Bafa in the Latmus region inland of Miletus suggests that a lightly grazed climax forest prevailed in the Maeander valley, otherwise untenanted. Sparse Neolithic settlements were made at springs, numerous and sometimes geothermal in this karst, rift valley topography. The islands offshore were settled perhaps for their strategic significance at the mouth of the Maeander, a route inland protected by escarpments. The graziers in the valley may have belonged to them, but the location looked to the sea.

The prehistoric archaeology of the Early and Middle Bronze Age portrays a city heavily influenced by society and events elsewhere in the Aegean, rather than inland.

The earliest Minoan settlement of Miletus dates to 2000 BC. Beginning at about 1900 BC artifacts of the Minoan civilization acquired by trade arrived at the site. For some centuries the location received a strong impulse from that civilization, an archaeological fact that tends to support but not necessarily confirm the founding legend—that is, a population influx from Crete. According to Strabo:

Ephorus says: Miletus was first founded and fortified above the sea by Cretans, where the Miletus of olden times is now situated, being settled by Sarpedon, who brought colonists from the Cretan Miletus and named the city after that Miletus, the place formerly being in possession of the Leleges.

According to Pausanias, however, Miletus was a friend of Sarpedon from Crete, after whom the city was named. Miletus had a son named Kelados, and the heroon of Kelados has been found at Panormos, a port of Miletus near Didyma.