The well-known Sienese family settled in Italy after the arrival of Charlemagne. In the Tuscan city, the Tolomei were able to take advantage of the process of change and became a powerful family of bankers, owners of towers and castles in the areas between the Montagnola Senese and the Maremma. To this family belonged the Pia dei Tolomei, quoted by Dante in the 5th canto of the Purgatorio (Purgatory), who tells of her death at the hands of her husband, who threw the woman from a window of his castle in the Maremma.
In the Siena area, then outside the city walls, the family owned a castle in the 11th and 12th centuries, which testifies to the wealth already achieved. The first palace was built before 1205. For this reason, it is the oldest private residence in Siena, but after 1267 it was only renewed on the upper floors, after the building had been almost completely destroyed by the Ghibellines. Reconstruction took place between 1270 and 1275. In 1277, the Tolomei residence burned down, but the building structure was not damaged. Today it is the result of a restoration in 1971 and is the seat of the Cassa di Risparmio di Firenze.
The grey stone façade of the palace shows the typical forms of the 13th century, with a very high ground floor and two floors separated by cornices and broken up by two rows of five elegant twin windows with pointed arches and trefoils.
In the hall there are restored architectural fragments that were found during the last restoration work.
In the Italian cult film The Grumpy Bear, starring Adriano Celentano, the Palazzo Tolomei serves as the central location in which the supposed loot of a 15 million euro bank robbery is said to be hidden. The plot, however, is entirely fictitious.