Careno, one of Nesso hamlets, has a characteristic upside-down triangle shape with the vertex at the lake where the small marina is located.
This shape is due to the fact that "careno" means rocky place and that most of the inhabitants worked high up in the stone quarries or were farmers or shepherds and only a minority was dedicated to fishing.
Immediately above the marina, at the top of the urban triangle, there is the Church of San Martino, one of the most interesting examples of Romanesque architecture in Lake Como.
The bell tower of the Masters Comacini is slender and has openings with single-arched windows that widen to double-arched windows going up towards the bell cell; the Church is very simple and has a wide stone cover.
The year of foundation is not known, but the small church was certainly built in the years before 1184, the year of the document signed by Pope Lucius III in which it is mentioned for the first time. The external characteristics also testify to the medieval origin of the structure.
San Martino was the parish church of the hamlet of Careno until, in the mid-seventeenth century, a new church was built, dedicated to Maria Assunta, to whom the parish benefit was transferred.