Foronikon Asty (=The city of Phoroneus), the name of Argos during prehistoric time, is by many considered to be the first town ever. The first settlement of modern day Argos took place in late 3rd millennium BC, during neolithic times. Since then, it's been continually inhabited and rebuilt in the same area, whereas it was first colonized in prehistoric times by the Pelasgian Greeks. Their historical presence in the area can be witnessed in the linguistic remainders that survive up to today, such as the very name of the city and "Larisa", the name of the city's castle located on the hill of the same name, meaning "citadel". During the Dorian invasion, circa 1098 BC, Argos was divided into four neighbourhoods, each of them inhabited by a different phyle.
A Neolithic settlement was located near the central sanctuary of Argois, at a distance of 45 stadia (8 km; 5 miles) from Argos, closer to Mycenae. The temple was dedicated to "Argivian Hera". The main festival of that temple was the Hekatombaia, one of the major festivals of Argos itself. Walter Burkert connected the festival to the myth of the slaying of Argus Panoptes by Hermes ("shimmering" or "slow"), and only secondarily associated with mythological Argus (or the toponym).
Argos was a major stronghold of Mycenaean times, and along with the neighbouring acropolis of Mycenae and Tiryns became a very early settlement because of its commanding positions in the midst of the fertile plain of Argolis. Argos experienced its greatest period of expansion and power under the energetic 7th century BC ruler King Pheidon. Under Pheidon Argos regained sway over the cities of the Argolid and challenged Sparta’s dominance of the Peloponnese. During this time of its greatest power, the city boasted a pottery and bronze sculpturing school, pottery shops, tanneries and clothes artisanships. Moreover, at least 25 celebrations took place in the city, in addition to a regular local products exhibition.
During Homeric times it belonged to a follower of Agamemnon and gave its name to the surrounding district; the Argolid which the Romans knew as Argeia.
The importance of Argos was eclipsed by Sparta after the 6th century BC; because of its refusal to fight or send supplies in the Greco-Persian Wars, Argos was shunned by most other city-states. Argos remained neutral or the ineffective ally of Athens during the 5th century BC struggles between Sparta and Athens.
ROMAN BYZANTINE MODERN
After Christianity became established in Argos, the first bishop documented in extant written records is Genethlius, who in 448 CE took part in the synod called by Archbishop Flavian of Constantinople that deposed Eutyches from his priestly office and excommunicated him. The next bishop of Argos, Onesimus, was at the 451 Council of Chalcedon. His successor, Thales, was a signatory of the letter that the bishops of the Roman province of Hellas sent in 458 to Byzantine Emperor Leo I the Thracian to protest about the killing of Proterius of Alexandria. Bishop Ioannes was at the Third Council of Constantinople in 680, and Theotimus at the Photian Council of Constantinople (879).
In the aftermath of the so-called Fourth Crusade, the Crusaders captured the castle called built on Larissa Hil, the site of the ancient Acropolis, and the area become part of the lordship of Argos and Nauplia. In 1388 it was sold to the Republic of Venice, but was taken by the despot of Mystra Theodore I Palaiologos before the Venetians could take control of the city; he sold it anyway to them in 1394.
In this period, Argos became a Latin Church bishopric, which lasted as a residential see until Argos was taken by the Ottoman Empire in 1463. Today, Argos is listed by the Catholic Church as a titular see.
In 1397, the Ottomans plundered Argos, carrying off much of the population, to sell as slaves. The Venetians repopulated the town and region with Albanian settlers, granting them long-term agrarian tax exemptions. Together with the Greeks of Argos, they supplied stratioti troops to the armies of Venice. Some historians consider the French military term "argoulet" to derive from the Greek "argetes", or inhabitant of Argos, as a large number of French stratioti came from the plain of Argos.
With the exception of a period of Venetian domination in 1687–1715, Argos remained in Ottoman hands until the beginning of the Greek War of Independence in 1821.
At that time, as part of the general uprising, many local governing bodies were formed in different parts of the country, and the "Consulate of Argos" was proclaimed on 28 March 1821, under the Peloponnesian Senate. It had a single head of state, Stamatellos Antonopoulos, styled "Consul", between 28 March and 26 May 1821.
Later, Argos accepted the authority of the unified Provisional Government of the First National Assembly at Epidaurus, and eventually became part of the Kingdom of Greece.