The complex history of construction of Como cathedral and its dome begins in XVI century, ends only in twentieth. It is strictly close with the urban image of the own town. Filippo Juvarra designed the dome of Como cathedral in 1731 and it was built in 1740. Immediately the Juvarra dome had many maintenance problems and this was the reason, thirty years after to redesign its profile. This was done by architect Giulio Galliori. The new profile of the dome, made of a wooden structure, was more appreciated from the contemporary people. The Galliori dome has represented the new urban simbol for the town of Como till 1935, when fire destroid it. This fact was an extraordinary opportunity to discuss if was better to rebuilt the original Juvarra dome or restored the wooden Galliori structure. This paper focus on the different value in the urban image of the dome of Como cathedral from Juvarra time till today