Siena's cathedral is one of Italy's most awe-inspiring churches. Construction started in 1215 and over the centuries many of Italy's top artists have contributed: Giovanni Pisano designed the intricate white, green and red marble facade; Nicola Pisano carved the elaborate pulpit; Pinturicchio painted some of the frescoes; Michelangelo, Donatello and Gian Lorenzo Bernini all produced sculptures. Buy tickets from the duomo ticket office.
This triumph of Romanesque-Gothic architecture has a truly stunning interior. Walls and pillars continue the exterior's striped theme, while the vaults are painted blue with gold stars. The intricate floor is inlaid with 56 panels depicting historical and biblical scenes executed by about 40 artists over 200 years from the 14th century on. The older rectangular panels, including the Wheel of Fortune (1372) and The She-Wolf of Siena with the Emblems of the Confederate Cities (1373), are graffiti designs by unknown artists. Domenico di Niccoló dei Cori was the first known artist to work on the cathedral, contributing several panels between 1413 and 1423, followed by renowned painter Domenico di Bartolo, who contributed Emperor Sigismund Enthroned in 1434. In the 15th century, director Alberto Aringhieri and celebrated Sienese artist Domenico Beccafumi created the dramatic expansion of the floor scheme. These later panels feature more advanced multicoloured marble, inlaid with hexagon and rhombus frames. Unfortunately, many panels are covered for much of the year, only being revealed between mid-August and October when the cathedral is open longer (from 10.30am to 7pm Monday to Saturday, and 9.30am to 6pm Sunday).
Other drawcards include the exquisitely crafted marble and porphyry pulpit created by Nicola Pisano, assisted by Arnolfo di Cambio, who later designed Florence's duomo. Intricately carved with vigorous, realistic crowd scenes, it's one of the masterpieces of Gothic sculpture. Over from the pulpit to the right of the transept, the Cappella del Voto harbours two marble statues of St Jerome and Mary Magdalene by baroque maestro Gian Lorenzo Bernini.
Donatello's famous bronze of St John the Baptist headlines in the Cappella di San Giovanni Battista, next to the Libreria Piccolomini. This enchanting library, accessible through a door from the north aisle, was built to house the books of Enea Silvio Piccolomini, better known as Pius II. The walls of the small hall are decorated with vividly coloured narrative frescoes painted between 1502 and 1507 by Bernardino Pinturicchio depicting events in the life of Piccolomini. Nearby, on the Piccolomini altar, you can admire four saintly sculptures by the young Michelangelo.
The duomo could have been grander still: in 1339 the city's medieval rulers drew up plans to enlarge it, creating one of Italy's biggest churches. The remains of this project, known as the Duomo Nuovo (New Cathedral), are on Piazza Jacopo della Quercia, on the eastern side of the cathedral. The daring plan to build an immense new nave with the present church becoming the transept was scotched by the plague of 1348.