I figured I should elaborate on one of the above meanings. All of the below information is from Dante's Divine Comedy. Specifically the first part, Inferno. I don't really believe it all but I do think it's cool to read.

Dis is basicaly the center of Hell and therefore the center of the Universe.

Hell can be divided into two main parts that are then divided into smaller sections called circles. One part is for sins of weakness. ex: Being born before Christ and therefore not Christian, lasciviousness, gluttony, incontinence, failing to choose a side (not having any religion). The other part is for willful sins. ex: blasphemy, sodomy, usury, and treachery.

The importance of this is that the City of Dis is where all the willful sinners go. The fiery city walls seperate the two parts of Hell. Satan is at the very center of the City and is embedded in ice while knawing on the three worst sinners, Brutus and Cassius(betrayed Caesar), Judas (betrayed Christ).