Piazza de Campo was erected when the Council of Nine controlled the town. During the Roman time the market was held here. Since the 1300s it has been civic and social meting point. The nine sectors int which its paving is divided remind inhabitants of the nine founders.
Part of the Fonte Gaia (fountain) here is just a copy of Jacopo della Quercia’s creation, which had to be removed because of weather damage. To see the originals head to the Complesso Museale di Santa Maria della Scala.
In the summertime the square can be a difficult place to walk around and practically impossible on the days when the famous Palio is held.
The Palazzo Comunale, Palazzo Pubblico or town hall stands proud over the square. The Council of Nine had it constructed in 1297, as a symbolic and centre of republican power with the aim of reducing the control of feudal knights.
The ground floor is constructed in stone while brick was used for the following storeys. The concave façade of the palazzo follows the shape of the convex piazza thus creating a perfect balance between both.
You can admire the courtyard of the palazzo free of charge, but there is an admission ticket for the Museo Civico sitting by the entrance of the palazzo (tel. 0577 29 22 63). The museum showcases frescoes which, unlike the widespread style of pieces of art from the era, are themed around secular subjects. They were created by the Sienese school. Decorations here as in many other buildings of Sienese style are generally profuse.
There is a room with pictures of artists, mainly of Sienese origin, ranging from the 16th to the 18th century.
In the Sala del Risorgimento there is a display of frescoes depicting the most important moments of the Unification of Italy.
The Sala di Balia is devoted to the struggle between the Sienese pope Alexander III and Frederick Barbarossa.
The following is the Anticamera del Concistoro keeping Ambrogio Lorenzetti’s Saints Catherine of Alexandria, John and Augustine.
From the Anticamera del Concistoro you can enter the Vestibolo that showcases, among other pieces, the wolf in bronze representing Siena. By the Vestibolo is the Anticappella. Frescoes depicting Greco-Roman mythological and historical events or characters hang on its walls. The chapel´s main attraction is Il Sodoma’s Holy Family and Saint Leonard and the finely carved choir stalls
From the chapel enter the Sala del Mappamondo housing the most admired pieces of the palazzo: Simone Martini’s Virgin Mary in Majesty. In this hall there are also other frescoes representing important events in Siena’s history with victorious outcomes.
Look up in the Sala del Concistoro to admire Domenico Beccafumi’s Mannerist ceiling frecoes.
The following room is the Sala dei Nove which keeps the Allegories of Good and Bad Government by Ambrogio Lorenzetti, considered by Francesco da Mosta to be one of the most captivating works in the country. The three panels of the fresco are said to have been painted for those in power to  encourage them to keep the values of a republic in mind: Justice, Wisdom, Virtue and Peace. The other frescoes Effects of Good Government and Effects of Bad Government are depictions of Siena filled with happiness and taken over by crime and death respectively.
For a good view from the palazzo go up to the loggia from where you can see for miles, beyond the city into the countryside.
Torre del Mangia, located by the Palazzo Comunale, the bell tower affording great views of Siena only allows 30 people up at a time. It is certainly worth the high climb. The 102m tower was designed in the Sienese style in 1344 and was a real triumph of engineering at the time.


Other great monuments to visit around the Piazza del Duomo, besides the cathedral are:
The Libreria Piccolomini which houses the collection of books that Enea Silvio Piccolomini (Pious II) left and that his nephew Pius III decided to keep in this library constructed especially to do so.
The hall was frescoed by Pinturicchio whose work show different events during those times. The hall is crowned by the Three Graces, a reproduction of a 3rd century Greek piece.
The Museo dell’Opera Metropolitana also known as the Museo dell’Opera Duomo sitting by the cathedral displays the original façade statues by Giovanni Pisano. As they were made to be seen from below as the faithful entered the cathedral they stretch forward and look rather unnatural.
The Majesty by Duccio di Buoninsegna was created in the 1300s. It was made to be placed on the high altar. Some parts of the panels depict Jesus preaching, praying or being kissed by Judas and being abandoned. Two nearby rooms house Jacopo della Quercia’s statues of the Fonte Gaia and another displays illustrations of the marble floor built in the 19th century.
Ambrogio Lorenzetti, Simone Martini and Taddeo di Bartolo’s works, tapestries and manuscripts are showcased on the upper levels.
Underneath the cathedral to the north is a crypt which remained filled with rubble for 7 centuries. Fortunately it was opened at the beginning of the 21st century, it is decorated with 13th century mural painting which covers 180 sq-m of biblical scenes.

The Baptistry of Saint John is located on Piazza San Giovanni. Its still not completed façade is an example of true Gothic magnificence and its interior full of frescoes. The apse has been decorated with frescoes representing the main events of Jesus´ life. The one portraying Jesus holding his cross has a particularly interesting background which shows buildings such as Brunelleschi’s Florentine dome and the campanile created by Giotto. In the rivalry between the Sienese and Florentines the Sienese were apparently trying to pin the blame on the Florentines for Jesus´suffering.
It could be said that the font is the most important element in this building.  It was created by Jacopo della Quercia who has represented the main events in Saint John the Baptist’s life. They were made in bronze relief panels. It is impossible not to admire the Baptism of Christ and Saint John in Prison by Lorenzo Ghiberti and Herod’s Feast by Donatello.