Said to be the oldest private Gothic palace in Siena, completed around 1208 for the Tolomei, one of the wealthiest of the city's noble families. The austere stone façade with paired Gothic windows on three floors set the model for Sienese palazzi for the next century.
It now houses a bank branch, with the ground floor partly accessible during business hours. The piazza outside is dominated by the church of San Cristoforo and used during the Palio by the contrada of the Civetta (owl), one of the 17 districts of the city.