"Are there any monsters in Canto XXXI and if so what purpose do they serve? If there are no "monsters" what does their absence signify?"
1. There are four monsters mentioned in Canto XXXI, these monsters were Nimrod, Ephialtes, Briareus, and Anataeus. These monsters were sentenced to stand between the eight and the ninth circle because they had challenged authorities who they were not supposed to do. The giant Nimrod "he is his own accuser./This is nimrod, because of whose vile plan/the world no longer speaks a single tongue." (Canto XXXI, 76-78). The second giant is Ephilates who rebelled against Jove. The third monster was Briareus, whom Virgil refused let Dante see. The fourth monster was Antaeus. Antaeus helped Dante and Virgil enter into the ninth circle. The monsters in this canto serve to help in the transition between the eight and the ninth circle. During this short journey that Dante and Virgil took to get to the monsters, Dante is seen to show fear as he approaches the giants.
Dante's error in mistaking the monsters for towers was corrected by Virgil and so the error turned into fear. The monsters in Canto XXXI are used to elaborate the situations that they are put into such as the fact that Antaeus as being, tall giant monster, carried Virgil and Dante below to the 9th circle of hell. By this, the author uses the traits of the monsters to make the scenery become active.
"What particular Topographical/geographical feature dominates this Canto?"
2. The topographical and geographical feature dominating Canto XXXI seemed as a city surrounded with towers of some sort. The area that the travelers, Virgil and Dante, were heading out to was covered in mist and fog. It was later on when Virgil explained to Dante that...