Built between 1228 and 1233 by order of the podesta Oldrado da Tresseno, this building was intended to be an autonomous seat for the independence
that Milan had won during the 12th century in its struggle against the German emperors.
At that time, the Palazzo della Ragione was made up only of the ground floor gallery and of the great hall used by judges and for assemblies, which is at the height of the three-light windows.
For centuries the palazzo was the law courts
of Milan, until the time when the Holy Roman Empress Maria Theresa transformed it into an archive for notarial deeds. It was then (1771-73) that the Palazzo della Ragione was enlarged with an elevation with large oval windows.
A strange relief on the portico towards Via Mercanti might be the reason for Milan to be anciently called "Mediolanum