Food and wine:
Sit on the Piazza del Campo, sip some wine and watch people and the world go by.
Eat a really late meal on the Piazza del Campo (summer only after all).
Eat outside somewhere, anywhere. And try wild boar (cinghiale).
To sample some of the local wines stop by the Cantina in Piazza located just off the Piazza del Campo (24 Via Casato Di Sotto).
Eat Chinese food.
Order a meal in Italian at Boccon del Prete on Via San Pietro. They'll help work you through it.
Experience an advanced civilization by picking any bar and watch Italians go about their business while you're sipping your caffe italiano.Stop at Nannini's on Via Banchi di Sopra for a Negroni Sbagliati (nay-grow-nee zbah-lee-ah-tee) aperitivo.
Visit one of the two cemeteries just outside the walls. Trust me on this.
Go to the Duomo for mass whether you're Catholic or not.
Take the evening stroll (passegiata) along with everyone else on Via Banchi di Sopra and Via di Citta.
Stop and say hi to Lisa at the Bookshop in the Galleria on Via San Pietro, and which just happens to be the only English-language bookshop in Siena (and where they occasionally have author's readings as well as children's storyime).
Go to the big open air market ("mercato"), held every Wednesday next to the Fortezza.
Take one of Roberto Bechi's tours of Siena and the hidden places nearby. We did and learned so much!
Study Italian for a couple of weeks at one of the language schools in the city.
Visit the Villa di Geggiano, just 5 kms from Siena. Dating back to the 13th century this villa, located on a hill overlooking the city, with its superb frescoed halls and rooms and beautiful gardens have belonged to the Bianchi Bandinelli family since the early 16th century. Wine tastings and tours available; ph. 0577 356879.
Some stuff to do that's nearby:
For wine stop at the enoteca in Montalcino -- but then drive over to Montepulciano and check out the Poliziano cantina on Piazza Grande in the city's historic center. We used to enjoy Avignonesi's tasting room but they're pretty much into selling "stuff" now so I'd pass in the future.
And while you're in Montepulciano stop at the handmade coppersmith's shop on 64 Via dell'Opio nel Corso, ph. 0578 758753, online: www.rameria.com. The shop is run by the smith himself and his wife and the quality of his workmanship is rivalled only by the reasonable cost.
The official Siena local government website is your best source for discovering what's happening in and around Siena and they also provide an excellent overview of the historic part of the city in addition to several handy city walks.
This is also the link to the website that has great tours of Siena:
look over some of this and let me know what you think baby.