Siena's museums are filled with fine examples of paintings and sculpture from the Romanic, Gothic and Pre-Renaissance periods. Aside from museums, the town is filled with Gothic architecture and the art of the Sienese school. You will not want to miss Siena's many small churches, and historical squares either. Here is a list of museums of interest:

Accademia dei Fisiocritici Museo di Storia Naturale
The collection includes geological, zoological, anatomical and botanical sections.
Address: Prato S.Agostino, 5 Piazzetta Silvio Gigli 2
Phone/Fax: 0577 47002
Website - More info: http://www.accademiafisiocritici.it

Archivio di Stato (Museum of the Biccherna Tablets)
Open only upon request in the mornings (closet Saturday and Sunday). In Palazzo Piccolomini, typical style of Florentine Renaissance, this museum holds the ancient tablets of the state ledgers and a collection of ancient manuscripts and books.
Address: Palazzo Piccolomini, Banchi di Sotto 52
Phone: 0577 247 145 / Fax: 0577 446 75
Ticket: Free

Battistero
Behind the Duomo, this baptistry holds a marble font by Jacopo della Quercia, with bronze panels depicting the life of Saint John the Baptist (designed by Lorenzo Ghiberti and Donatello amongst others).

Duomo of Siena
Siena's Duomo (Cathedral) and its Libreria Piccolomini (holds frescos which tell the story of the life of Pope Pius II, and elaborately illustrated books). The Duomo also hold precious frescos, sculptures, stained glass designs and marble masterpieces.

Museo dell'Opera del Duomo
Located in the corner where the larger Duomo would have been. Sacred works from 1300 to 1500 are found here, including work by Duccio. In the Galleria della Statua, you will find the sculpture of Giovanni Pisano, titled Jacopo della Quercia a Donatello. There is an outdoor walkway with a panoramic view of Siena, which is not to be missed.
Address: Piazza del Duomo, 8
Phone: 0577 42309 - 283 098 / Fax: 0577 280 626
Website - More info: http://www.operaduomo.siena.it/

Museo Civico (Civic Museum)
At Palazzo Pubblico, the Museo Civico holds masterpieces of Sienese art. The astronomical frescos in the Sala del Mappamondo and the Sala della Pace are not to be missed. Frescos from the 19the century, which depict Italy's first king, can also be found there. You can climb to the top of the bell tower (Torre del Mangia), for a stunning view of Il Campo, Siena and the surrounding countryside.
Address: Palazzo Comunale, Il Campo (Via), 1
Phone: 0577 292 226 / Fax: 0577 292 296

Museo d'Arte per Bambini (Art's museum for kids)
A specific section with activities and programs designed to offer children exposure to art is located inside the monumental complex of Santa Maria della Scala.
Address: Piazza Duomo, 1
Phone: 0577 534511

Museo della Società Esecutori Pie Disposizioni (Museum of the Society of Executors of Charitable Funds)
Open to the public since 1938, this museum contains an interesting collection of works of art from the Sienese school from the 14th - 18th C. Some notable works are La Sacra Famiglia con San Giovannino of Sodoma and Santa Caterina conduce a Roma il Papa of Girolamo of Benvenuto. Working hours: Mon-Fri 9.00-13.00, Tue and Thu 15.00-17.00. For groups reservation is required.
Address: Via Roma 71
Phone: 0577 284 300

Museo Geomineralogico e Zoologico
Geological/Mineralogical/Zoological Museums
Address: Accademia dei Fisiocritici, Prato di S. Agostino 5
Phone/Fax: 0577 47002

Oratorio di S.Bernardino (Oratory of S. Bernardino)
Built during the 1400s, the interiors feature Mannerist frescoes by Domenico Beccafumi. Beautiful wood and wall paintings are found in this baptistry, located near San Francesco Church.
Address: Piazza San Francesco
Phone: 0577 283 048 / Fax: 0577 280 626

Pinacoteca Nazionale (National Picture Gallery)
This museum holds the largest collection of Sienese paintings, including great masters from the 12th century through the first half of the 17th century and works painted on backgrounds of gold leaf. Discover masterpieces by Duccio di Buoninsegna, Simone Martini, Pietro and Ambrogio Lorenzetti and other artists of the Sienese School here.
Address: Palazzo Buonsignori, S. Pietro (via di), 29
Phone: 0577 281 161 - 286 143 / Fax: 0577 270 508

Santuario Di Santa Caterina Da Siena
This popular tourist spot was once the home of Saint Catherine. Inside, you can see the Oratorio della Cucina (built around 1482) which was once the family kitchen, and the Oratorio della Camera where Siena's patron saint once rested.
Address: Costa di S. Antonio/ corner Via Fontebranda

Santa Maria della Scala Complesso museale (Santa Maria della Scala Hospital)
What is now a museum was once of Europe's first hospitals that offered pilgrims hospitality, and extended its care to the poor and homeless. Inside, you will find a fine collection of work by Sienese artists, and a look at life of the "Spedale," depicted in frescoes that decorate the Sala del Pellegrinaio.
Address: Piazza del Duomo, 2
Phone: 0577 224 811 / Fax: 0577 224 829
Website - More info: http://www.santamaria.comune.siena.it

Sinagoga
Located behind Piazza del Campo, the old Synagouge of Siena can be visited on Sundays.
Address: Via delle Scotte 14
Open only on Sundays.