Piero and Giuliano for some time lurked in the Casentino, with Bernardo Dovizi at Bibbiena. [57] The lover of Florentine history cannot readily tear himself away from the Casentino. The Albergo Amorosi at Bibbiena, almost at the foot of La Verna, makes delightful headquarters. There is an excellent _Guida illustrata del Casentino_ by C. Beni. For the Conti Guidi, Witte's essay should be consulted; it is translated in _Witte's Essays on Dante_ by C. M. Lawrence and P. H. Wicksteed. La Verna will be fully dealt with in the Assisi volume of this series, so I do not describe it here. Throughout the Casentino Dante himself should be our guide. There is hardly another district in Italy so intimately connected with the divine poet; save only Florence and Ravenna, there is, perhaps, none where we more frequently need to have recourse to the pages of the _Divina Commedia_. With the _Inferno_ in our hands, we seek out Count Alessandro's castle of Romena and what purports to be the Fonte Branda, below the castle to the left, for whose waters--even to cool the thirst of Hell--Maestro Adamo would not have given the sight of his seducer sharing his agony. With the _Purgatorio_ we trace the course of the Arno from where, a mere _fiumicello_, it takes its rise in Falterona, and runs down past Porciano and Poppi to sweep away from the Aretines, "turning aside its muzzle in disdain." There is a tradition that Dante was imprisoned in the castle of Porciano. We know that he was the guest of various members of the Conti Guidi at different times during his exile; it was from one of their castles, probably Poppi, that on March 31st and April 16th, 1311, he directed his two terrible letters to the Florentine government and to the Emperor Henry. It was in the Casentino, too, that he composed the Canzone _Amor, dacchè convien pur ch'io mi doglia_, "Love, since I needs must make complaint," one of the latest and most perplexing of his lyrics.