Ermoupoli (Greek: Ερμούπολη), also known by the formal older name Ermoupolis or Hermoupolis (Greek: Ἑρμούπολις < Ἑρμοῦ πόλις "Town of Hermes"), is a town and former municipality on the island of Syros, in the Cyclades, Greece.
It soon became the leading commercial and industrial center of Greece, as well as its main port.
The renowned Greek Steamship Company was founded in the city in 1856.
In the following decades the city declined, remaining the administrative center of the Cyclades islands.
In the end of the 20th and the beginning of the 21st century, its economy has significantly improved, based on the sectrors of services, industry, education and tourism.