The most ancient palace in the Piazza dei Priori is Palazzo dei Priori, the present day Town Hall designed by Richard of Como. Building work began in 1208 and was completed in the middle of the 13th century. The façade has gone through several changes over the centuries. The windows on the second and third floors still preserve their original Romanesque structure, while those on the first are trilobed mullioned windows with a slightly pointed arch. The clock interrupts the uniformity of the façade as it was added at a later date, as was the crenellation that crowns the palace. The original tower terminated at the first crenellation and was once surmounted by a wooden bell tower, but after the earthquake in 1846 it was rebuilt in stone. The entrance has a cross vaulted ceiling and is adorned with coats of arms and glazed medallions. Along the stairway leading up to the first floor there is a fresco of the Crucifixion by Pier Francesco Fiorentino (15th century).