Built between 1212 and 1305, this was the first public building to be erected in Piazza del Comune.
The facade of the building contains the measures for silk, linen and wool, as well as the outlines of bricks and roof tiles used in building.
The first fresco in the cycle of the life of St Francis shows the Palazzo del Capitano del Popolo
without the upper part of its tower, which was not added until 1305.
Restoration work carried out in 1927 considerably altered the original appearance of the building.