The Church of San Pietro in Banchi is a remarkable example of a religious building placed above commercial activities, in a curious mixture of the sacred and the profane. Raised above the level of the square, in fact, it is built on a plinth housing some shops; the portico is crowned by a frescoed façade on which a double row of three normal windows opens; the dome of the apses is only visible when looking at it from below. 
The church was built thanks to the proceeds from the sale of commercial premises, a compromise between the wishes of the Lomellino family - who wanted to use the area for commercial purposes - and the wishes of the population, who wanted to erect a church to fulfil a vow.