Citta` di Travertine
Ascoli Piceno is known as the city of travertine. When you see photos of places like Roma it looks like many of the buildings are made of marble, but beneath many of these grand-looking facades lies a brick base with a thin travertine veneer. Not so Ascoli Piceno. This town has an abundance of travertine in the nearby mountains and has made full use of it in constructing its buildings from solid blocks of stone.
The Valle Tronto to the west has several quarries that are visible as you drive the Via Salaria, which supplied building materials for Ascoli as well as the other cities in this valley. This is contrasted with the cities north and east of Ascoli which are all mostly brick, travertine was only used for important civic buildings.
Travertine is a sedimentary rock formed in bodies of water as calcium carbonate settles to the bottom. It is not marble but many times the word will be translated to “marble” here in Italy, and I’ve seen travertine countertops in the US labeled as marble, as well. When you look at it closely you can see the layering of the strata which makes it porous. Travertine can be cut into thin slabs and polished, which are commonly used on walls and floors (and dividers in fancy hotel lobby bathrooms). It can also be carved and there are many fine examples of finely-carved travertine here in Ascoli, especially on the entry portals to Chiesa San Francesco.
The majority of the buildings here are built from solid blocks of the stuff, with its use extended to such things as lintels, window sills, door frames, and floors; the grand Piazza del Popolo is paved with polished travertine. The solid foundation of these buildings is a testimony to why this city has survived since before the founding of Roma.