A number of house inscriptions, the oldest of which dates from 1515, indicate that the house from Malvaglia in the Blenio Valley is of considerable age. The “Casa San Carlo” owes its name to a legend that tells how the counter-reforming Cardinal Carlo Borromeo spent the night in this house on one of his pastoral visits.
The original building must have had an archaic appearance. The single-storey block structure was supported on pillars approximately two metres above the ground. It is assumed that the low-pitched “Tätsch” roof was covered earlier with board shingles. This assumption is substantiated by an ordinance on customs tariffs dating from 1639 which shows that shingles were exported from the Blenio Valley. When a second full storey was added in 1564, the pillar foundation was strengthened by constructing walls around and between the pillars so as to make it into a basement. A notable detail of the storey containing the living quarters is the open vestibule with an opening for tending the stone heating stove.
When it was dismantled, the building was roofed with stones. On its reconstruction in the museum, a number of structural problems resulted from this load of more than 35 tons. The front gable side, for instance, had to be reinforced with a support structure.
On closer examination this house, which at first sight appears to be without ornament, is seen to have a number of carvings. In addition to dates and initials, the crosses carved above the door and windows particularly spring to notice. These religious signs, and the proximity of the house to a church at its previous site, suggest that it could have formerly been a priest’s house. The capital letters IO/AN/IS beside the date 1564 on the door lintel of the parlour on the upper floor refer either to St. John (“Johannes”) or to the house owner.