In Ripa del Sale, the slip surface that separates the Cathedral from the Town Hall, is the Palazzo Rospigliosi; built in the mid-sixteenth century by Giovan Battista Rospigliosi, said Bati, which he grouped together several existing buildings in the area of ​​the first city walls. The façade, perfectly in line with the models of the late Florentine mannerism, shows the monumental entrance portal that opens on the street with an elegant double staircase.

Path the entrance corridor in which dominates an ancient family coat of arms, painted wood, leads to the first floor of the building to the right where there is the input to two separate, albeit contiguous, museum units: the Clemente Rospigliosi Museum and the Diocesan Museum.