Layers of mountain โฐ๏ธ

Seventeenth-century arches made from piedra ostionera (“oyster stone”), a porous sandstone containing oyster shells and other fossilised creatures. I really like how it looks and feels. ๐๏ธ

I wonder if the arch is purely decorative, or whether it functioned differently before being filled in. ๐ช๐ช๐ช
