Piazza Tolomei is one of the oldest squares in Siena and is located on the main pedestrian area of Via Banchi di Sopra. In the piazza, two buildings that remember Siena's earliest history in its current form catch your eye:

Chiesa San Cristoforo - It is one of the oldest Sienese buildings ever. Its original 11th-century Romanesque style is evident in the interior of the church, but the façade was rebuilt in a neoclassical style during the 18th century. Entrance to the church is free.
Palazzo Tolomei - One of the oldest palaces in the city, completed in 1275 by the wealthy Tolomei family. For the first years it served as the main seat of the Sienese commune, later as a bank.