Perhaps constructed by Perugians around 1375-76, the building, Palazzo Comunale, is situated on the most ancient Palazzo dei Priori. In the past it was called the Palazzo del Pietrone, referring to the large stone on which the Mayor’s orders and citations were concentrated. The Palazzo del Pietrone was provided with an external stairway from which the announcements were read. It was covered in paintings and sculptures representing the arms of the various mayors and other rectors of the Castiglion municipality. The Statute prohibited this practice due to the damages it did to the palace’s walls.
Between 1324 and 1336, the building became run down. In fact, the assemblies of the Council were no longer held there all throughout 1353; they were held in the Church of S. Francesco. It was restructured in 1489, when the Room for the General Council was built. In 1717 this was used as a theatre.
In 1512 and 1560, the balustrade of the stairway was built in stone. Around 1568, a stone tablet on which the linear measurements used in the community were written, was placed in the atrium. According to the medieval practice, all of the dimensions of construction bricks had to follow this measurement.
The current layout of the palace corresponds to the 1935 renovations when, based on the project by architect Castellucci, the façade was normalized and the civic Tower reconstructed.