Magnesia or Magnesia on the Maeander is an ancient Greek city in Ionia, considerable in size, at an important location commercially and strategically in the triangle of Priene, Ephesus and Tralles.

The city is named Magnesia, after the Magnetes from Thessaly who settle the area along with some Cretans.

It is later called "on the Meander" to distinguish it from the nearby Lydian city Magnesia ad Sipylum.The territory around Magnesia is extremely fertile, and produces excellent wine, figs, and cucumbers.

It is built on the slope of Mount Thorax, on the banks of the small river Lethacus, a tributary of the Maeander river upstream from Ephesus.

It is 15 miles from the city of Miletus.

The ruins of the city are located west of the modern village Tekin in the Germencik district of Aydın Province, Turkey.Magnesia lies within Ionia, but because it had been settled by Aeolians from Greece, is not accepted into the Ionian League.

Magnesia may have been ruled for a time by the Lydians, and is for some time under the control of the Persians, and subject to Cimmerian raids.

In later years, Magnesia supportesthe Romans in the Second Mithridatic War.