the casentino is the valley in which the first tract of the arno river flows till subbiano, in the italian region tuscany. it is one of the four valleys in which the province of arezzo is divided. the valley's biggest "comuni" are all in the arno valley: among these the biggest are bibbiena and poppi, while capolona, castel focognano, castel san niccolò, pratovecchio, stia, subbiano are more or less smaller. the villages on the neighbouring hills and mountains are much smaller. these are chitignano, chiusi della verna, montemignaio, ortignano-raggiolo and talla. the casentino is mentioned in the song "ich hab in penna einen liebsten wohnen", from the "italieniches liederbuch" by hugo wolf.