The settings that we encounter in the Inferno reveal Dante's opinions about justice. Dante has created a world in which the sins that he believes are more rampant in the world are punished in ways that he believes are fair. Therefore, the settings reveal a lot about Dante's mind, as well as his social, political and historical context.
For example, at the entrance of Inferno, Dante encounters Limbo. Limbo is the place where virtuous people who did not believe in God are. This reveals that Dante believes pagans (people who do not believe in Christianity) can still be virtuous people, and therefore do not deserve a cruel punishment. Another example is the Fourth Circle of Hell, where people who were consumed by greed are located. Here, Dante finds both people who hoarded wealth as well as people who squandered it. This shows that Dante believed both of these to be equally negative and equally deserving of punishment and justice.