Lemon growing

Gargnano was the site of an early industry in the growing of citrus fruits helped by the mild climate. During the 15the century special buildings were constructed for their cultivation with walls on three sides to protect the trees with the stone retaining the heat making it possible for the fruit to ripen. The photo shows the remains of a building of a similar style - I don’t think it dates from the 15th century.
Citrus trees still abound but the industry has moved on to Southern Italy with the ease of modern transport.