Inside the Palazzo Coli Bizzarini formerly Francesconi, the most important example of Sienese architecture of the 1500s based on a project by the great architect Baldassarre Peruzzi. Now divided into two elegant, ready-to-live-in units which they offer incredible views of the city, the Torre del Mangia and the Duomo. The palace is protected by the Fine Arts even if Peruzzi left the work unfinished following the assignment by Agostino Chigi for the construction of the villa La Farnesina in Rome. Bernardo Francesconi commissioned the palace to Peruzzi, magistrate and skillful politician belonging to a prestigious noble Sienese family. On the facade remain the heraldic elements in the frames of both the Tolomei and the Piccolomini, two other important Sienese families. As only in some great works such as Palazzo Farnese in Rome and Palazzo Strozzi in Florence, here as well the laying of the first stone of the building was celebrated by inserting a bronze medal reproducing Francesconi's face as proof that the work had to be one of the most impressive and important in the city. In 1788 it passed to the Mocenni family and was then purchased by the Noble Chemist-Pharmacist Elia di Raffaello Coli and his wife Zulmira Bizzarrini, another noble Sienese family whose family has owned and preserved it for over 132 years.​
The penthouse is located on the fourth floor of the building and can be accessed from the main door via the elegant and comfortable Travertine stone staircase or it is possible to use the elevator owned exclusively by the current owner. The two units are currently divided as follows: on the left is the 128sqm apartment, consisting of a large living room with three windows that give a lot of light to the environment and a precious parquet and grit floor, on the ceiling beams and terracotta tiles preserve the authentic taste of the property, expertly furnished with prestigious finishes. In addition to a bedroom, a kitchen and a bathroom, the large room dedicated to the kitchen is currently used as a bedroom to optimize space and the current tourist rental business as a period residence which is conducted on the two units. The other apartment with an entrance to the right of the stairs is 101sqm with a living room, kitchenette and a bedroom with bathroom. A jewel in the heart of the city of Siena and an unmissable opportunity to purchase a piece of history, ideal not only for living thanks to its central and convenient location, but also an excellent investment to generate income by continuing the profitable work currently carried out by the property itself .