Siena, like many other Tuscan hill towns, was first settled in the time of the Etruscans (c. 900 BC to 400 BC) when it was inhabited by a tribe called the Saina.
The Etruscans were an advanced people who changed the face of central Italy through their use of irrigation to reclaim previously unfarmable land, and their custom of building their settlements in heavily armoured hill-forts. It has been argued that their pagan society which practiced matrilineal inheritance, and was devoted to their goddesses was one of the reasons why Roman Goddesses such as Diana and, with the arrival of Christianity, the Virgin Mary came to be of such importance to the people of the Italian peninsula. If this is true, it suggests that the Cult of the Virgin which is omnipresent in the fabric of Siena's ancient stones has an origin which is older still.
What we can say for certain is that the Romans founded a town called Saenna Julia on the site of a pre-existing Etruscan settlement, and from this has grown modern Siena. Siena may then have been under the control of invading Gaulish forces – who are known to have sacked Rome in 390 BC. Some archaeologists assert it was controlled for a period by a Gaulish tribe called the Saenones.
The Roman origin accounts for the town's emblem – a she-wolf suckling the infants Romulus and Remus. According to legend, Siena was founded by Senius, son of Remus, who was in turn the brother of Romulus, after whom Rome was named. Statues and other artwork depicting a she-wolf suckling the young twins Romulus and Remus can be seen all over the city of Siena. Other etymologies derive the name from the Etruscan family name "Saina", the Roman family name of the "Saenii", or the Latin word "senex" ("old") or the derived form "seneo", "to be old".
Siena did not prosper under Roman rule. It was not sited near any major roads and therefore missed out on the resulting opportunities for trade. Its insular status meant that Christianity did not penetrate until the fourth century AD, and it was not until the Lombards invaded Siena and the surrounding territory that it knew prosperity. Their occupation and the fact that the old Roman roads of Aurelia and the Cassia passed through areas exposed to Byzantine raids, caused the roads between the Lombards' northern possessions and Rome to be re-routed through Siena. The inevitable consequence of this was that Siena prospered as a trading post, and the constant streams of pilgrims passing to and from Rome were to prove a valuable source of income in the centuries to come.
The oldest aristocratic families in Siena date their line to the Lombards' surrender in 774 to Charlemagne. At this point the city was inundated with a swarm of Frankish overseers who married into the existing Sienese nobility, and left a legacy that can be seen in the abbeys they founded throughout Sienese territory. Feudal power waned however, and by the death of Countess Matilda in 1115 the Mark of Tuscia which had been under the control of her family – the Canossa – broke up into several autonomous regions.
Siena prospered under the new arrangements, becoming a major centre of money lending and an important player in the wool trade. It was governed at first directly by its Bishop, but episcopal power declined during the 1100s. The bishop was forced to concede a greater say in the running of the city to the nobility in exchange for their help during a territorial dispute with Arezzo, and this started a process which culminated in 1167 when the commune of Siena declared its independence from episcopal control. By 1179, it had a written constitution.
This period was also crucial in shaping the Siena we know today. It was during the 1100s that the majority of the construction of the Duomo, Siena's cathederal, was completed. It was also during this period that the Piazza del Campo, now regarded as one of the most beautiful civic spaces in Europe, grew in importance as the centre of secular life. New streets were constructed leading to it and it served as the site of the market, and the location of many sporting events (perhaps better thought of as riots, in the fashion of the Florentine football matches that are still practised to this day). A wall was constructed in 1194 at the current site of the Palazzo Pubblico to stop soil erosion, an indication of how important the area was becoming as a civic space.
In the early 12th century a self-governing commune replaced the earlier aristocratic government. The consuls who governed the republic slowly became more inclusive of the poblani, or common people, and the Commune increased its territory as the surrounding feudal nobles in their fortified castles submitted to the urban power. Siena's republic, struggling internally between nobles and the popular party, usually worked in political opposition to its great rival, Florence, and was in the 13th century predominantly Ghibelline in opposition to Florence's Guelph position (the backdrop for Dante's Commedia).
On September 4, 1260 The Senese Ghibellines, supported by the forces of King Manfred of Sicily, defeated the Florentine Guelphs at Montaperti. The Senese faced an overwhelming Florentine army. Prior to the battle, the entire city was dedicated to the Virgin Mary and entrusted to her possession – something which has been renewed several times since, most recently in 1944 to guard the city from the threat of Allied bombs. The man given command of Siena for the duration of the war, Bonaguida Lucari, walked barefoot and bareheaded, a halter around his neck, to the Duomo. Leading a procession composed of all the city's residents, he was met by all the clergy. Lucari and the Bishop embraced, to show the unity of church and state, then Luceri formally gave the city and contrade to the Virgin. Legend has it that a thick white cloud descended on the battlefield, giving the Senese cover and aiding their attack. They inflicted a crushing defeat and massacred the forces of their enemy, so crushing was the defeat that even today if the two cities meet in any sporting event, the Senese supporters are likely to exhort their Florentine counterparts to “Remember Montaperti!”.
Siena's university, founded in 1203 and famed for its faculties of law and medicine, is still among the most important Italian universities. Siena rivalled Florence in the arts through the 13th and 14th centuries]]: the important late medieval painter Duccio (1253–1319) was a Senese, but worked across the peninsula, and the mural of "Good Government" by Ambrogio Lorenzetti in the Palazzo Pubblico, or town hall, is a magnificent example of late-Medieval/early Renaissance art as well as a representation of the utopia of urban society as conceived during that period. Siena was devastated by the Black Death of 1348 and never recovered its earlier glory, losing out to Florence in inter-urban rivalry.
Siena retained its independence in Tuscany until the 16th century. In 1554 Cosimo I de' Medici collected a large Florentine-Imperial army and laid siege to the city, which entrusted its defence to Piero Strozzi. When the latter was defeated at the Battle of Marciano (August 1554), any hope of relief was lost. After 18 months of resistance, it surrendered to Florence on April 17, 1555, marking the end of the Republic of Siena.
The picturesque city remains an important cultural centre, especially for humanist disciplines.