Siena historical timeline

Siena's history has an unusual shape for a great Italian city: it peaks early, loses decisively, and then stops. The republic was Florence's most serious rival for two centuries; the Black Death removed half its people; the war ended in 1555 with the republic abolished; and the city has been roughly the same size ever since. Everything a visitor admires survives because nothing came along to replace it.

Chronology

1. c. 900–400 B.C. — The area is settled by the Saina, from whom the city takes its name. The Etruscan presence leaves little above ground here compared with the coastal cities, but it fixes the site: defensible clay ridges above the surrounding country.
2. 1st century B.C. — Rome establishes the town of Saena Iulia under Augustus. It remains minor throughout the Roman period, off the main roads, which is part of why Siena developed late and then very fast.
3. 1115 — Countess Matilda dies, feudal authority over the area weakens, and Siena begins to govern itself. The twelfth century turns it into an independent commune and then a republic with territorial ambitions — and a direct, permanent rivalry with Florence thirty miles north.
4. 13th century — Siena becomes a European banking centre, financing papal and commercial business across the continent. This is where the money comes from, and it is spent on the two things a visitor comes to see: the cathedral, and the civic centre around the Campo.
5. 1297 — Work begins on the Palazzo Pubblico on the lower edge of Piazza del Campo, and the square is laid out as a shell-shaped slope divided into nine segments for the Council of Nine, the oligarchy that governed the republic at its height. The division is still visible in the brick, which makes the pavement a diagram of the constitution.
6. 1339 — The republic begins the Duomo Nuovo, an enormous new nave intended to make Siena's cathedral the largest in Christendom, with the existing building reduced to a transept. It is the high-water mark of Sienese ambition.
7. 1348 — The Black Death arrives. The city had held about 50,000 people; the plague removes a catastrophic share of them and with them the labour, revenue and confidence to continue. The new nave is abandoned where it stood. Its standing wall and single aisle — the Facciatone — are still there in open air, which makes 1348 the most physically legible date in the city.
8. 1555 — Spanish and Florentine forces defeat Siena and the republic is abolished after a long and ruinous war. The city passes into the Tuscan state governed from Florence, and its political life ends. Its medieval fabric is thereby frozen: there is no money for a Renaissance rebuilding and no reason for one.
9. 1737 — Tuscany passes to the Habsburg-Lorraine dynasty. Siena spends the eighteenth and nineteenth centuries as a provincial town, and the contrade consolidate into the form they still have — neighbourhood communities with their own churches, fountains, officials and rivalries, which become the city's real civic structure in the absence of a republic.
10. 17th–18th centuries — The Palio settles into its modern form, run around the Piazza del Campo on fixed dates in July and August. It is not revived folklore: it is the continuous practice of the contrade, which is why it remains their event rather than a performance.
11. 1859 — Siena votes to join the Kingdom of Sardinia, and so enters unified Italy. The city gains a railway, but on a secondary line rather than a main one — a position that has shaped its accessibility ever since and is a large part of why it is still a day-trip destination rather than a hub.
12. 1995 — The historic centre of Siena is inscribed as a UNESCO World Heritage Site under cultural criteria i, ii and iv. Criterion (i) is the significant one: it marks the city itself, not a district within it, as a masterpiece of human creative genius. The inscription formalises what the defeat of 1555 accidentally preserved.
13. 2026 — The municipality holds 53,180 people — about three thousand more than before the plague of 1348. Siena is the rare European city whose population graph is essentially flat across seven centuries, and that flatness is the single best explanation of why it looks as it does.