In cities and towns, stone slabs were used for paving the streets, both in principal routes using large size pieces, as well as for secondary roads which led off from the market; where carriages were intended to pass, two long strips of slabs were laid (called lasagne). The various Ossola stone materials can be seen in classical architectural structures such as in the construction of doorways, colonnades, sills, window and door posts and lintels, and even to make typical Roman eaves. Slabs were preferred, instead, in the construction of balconies using stone shelves where decoration were also applied.

If granite was almost always used in paving, then for roof ridges and coverings the preference was towards using beola slabs because of their elevated resistance to water and for the fact that they are easier to work whit. Granite and serizzo were employed for grinding wheels and with structural elements for bridges, strongholds and castles.
Considering that manual labour once cost very little, the cost of using stone was justifiable even for commonly used domestic objects, such as stoves, "furnet" for heating purposes, presses, mortars, and even benches and tables, and for tubing purposes. Although rare nowadays, the "laveggi" of Val d'Ossola were once common objects: large containers made from green, serpentine rock called "pietra laugera".

The Candoglia marble is a unique identity. In ancient times, it was traditionally accepted that one could quarry the stone materials required for the building of one's house from one's own land. This quarrying activity could also be done on town property, at locations that were approved by consuls in accordance whit "Diritto Spedifico di Vicini" (right-of-way concessions) which were usually only conceded to residents. Later, the king took away this right and granted it only if given a royalty. The right to quarry stone for economical gain was given only after the payment of an adequate price.
This situation repeated itself at the quarries of Candoglia and Crevola which, for a certain period, belonged to eleven Townships, but which soon fell to royal control, and after which were subsequently sold or granted. On October 24, 1387, Gian Galeazzo Visconti, the Duke of Milan, granted the Deputati della Veneranda Fabbrica del Duomo (Deputies of the Venerable Vestry of the Duomo) the right to quarry at Candoglia for marble required to build the Duomo, along with the right to transport it to Milan, without having to pay taxes or tolls. It is not exactly clear why Candoglia marble was chosen, especially given the fact that deposits were reportedly scarce. Certainly the quarry's location near the River Toce made trasporting 20-ton blocks on 15-18 metre rafts much easier, a fact which may have tipped the balance in favour of this choice. And this is without considering the political side to the choice: it allowed Gian Galeazzo Visconti to possess advanced commercial and military means of transportation for his Ossola quarries.

As in the past, Candoglia marble is still primarily used for the continuous restoration works of the Duomo of Milan. The rights were extended to include the entire, current and future, deposits and outcrops. He did permit that marble could be excavated in the towns of Mergozzo, Bracchio, Candoglia and Albo, but for pernal use only.