Duomo di Siena (Cattedrale Metropolitana di Santa Maria Assunta)

Siena's cathedral condenses the ambitions of the medieval republic into one striped block of marble. Inside, fifty-six inlaid marble panels unfold like an illustrated manuscript, with sculpture by the Pisano, Donatello, Michelangelo and Bernini in the aisles. When the floor is uncovered in summer and autumn, few interiors in Italy can match it.

Why it matters

No other building concentrates Siena's artistic ambition so completely. Its striped columns, carved capitals and inlaid pavement were the work of the city's leading workshops across six centuries, and the treasury of medieval sculpture collected here — Nicola Pisano's sculpted pulpit, Giovanni Pisano's facade statues, Donatello's bronze Saint John the Baptist, Bernini's Mary Magdalene — has few equals in any single Italian church. The Opera della Metropolitana, the institution that has administered the building since the Middle Ages, still runs it today.

What to notice

Begin with the floor. Two techniques alternate: graffito, where a design is cut into white marble and filled with dark stucco, and mosaic marble inlay, assembled like marquetry. Fifty-six panels carry designs prepared by leading Sienese painters — Matteo di Giovanni's Slaughter of the Innocents, the Sibyls of 1482–1483, Domenico Beccafumi's Old Testament hexagons, and Pinturicchio's 1505 Mount of Wisdom, the only panel designed by a non-Sienese. Vasari praised this pavement as the largest and most magnificent ever made.

Then look up and around: Duccio's great rose window hangs as a copy in situ, the original kept in the museum next door, and the pulpit carved by Nicola Pisano between 1265 and 1268 stands among the founding monuments of Gothic sculpture. Along the left aisle, Michelangelo's four saints belong to the Piccolomini altar, which opens onto the Piccolomini Library.

Context and history

Tradition places an earlier church dedicated to the Virgin on this spot from the ninth century, and one unconfirmed account records a consecration in 1179 under the Sienese pope Alexander III. The first firm document is a payment of April 1259 to a certain Magister Nicolaus of the Opera Santa Maria — very likely Nicola Pisano. Lead bought for the dome in 1263 shows it was finished by then, though the lantern was rebuilt in 1667. Giovanni Pisano directed the works from 1284 to 1297 and shaped the lower facade with its prophets, sibyls and philosophers; the originals were replaced by copies in the nineteenth and twentieth centuries and are now displayed in the Museo dell'Opera. An audacious plan in 1339 to enlarge the church ended with the plague of 1348; its remnants include the unfinished facade known as the Facciatone, whose viewing terrace is recorded separately. The floor's decoration continued from the fourteenth century into the nineteenth.