Commentary Par XV 109-111

The thought here is that Florence after Cacciaguida's day rapidly eclipsed Rome in urban splendor, but its fall from supremacy will be even more swift.  In synecdoche, Monte Mario and Uccellatoio represent Rome and Florence respectively.  Explaining these lines, Carroll has this to say (DDP Carroll.Par.XV.97-120): 'Montemalo (now Monte Mario) is the hill on the way from Viterbo from which the splendour of the Eternal City is first seen; and Uccellatoio is the point on the road from Bologna from which the first flash of the greater splendour of Florence breaks on the traveller's view.'