One of the parts of The Divine Comedy I find interesting is that it is an extremely effective demonstration to point people who still believe the hard-to-kill myth that the idea of a round Earth was unknown to Europeans before Columbus to, because of the sheer level of detail Dante goes into about it.
Purgatorio, canto II [1] in particular explicitly "place" purgatory at the opposite side of the globe from Jerusalem, and describe in detail how different stars are visible, and how the time is different in Jerusalem, over Ganges and in Purgatory, as well as how the seasons are different in the southern hemisphere. The differences between the hemispheres etc. are revisited several times to make explicit how Purgatory differs, for example in Purgatorio, canto IV, verse 55 onwards [2].
The Divine Comedy also underlines that in the pre-Galilean European cosmology, the centre of the universe was not in fact considered the best place to be ...
Purgatorio, canto II [1] in particular explicitly "place" purgatory at the opposite side of the globe from Jerusalem, and describe in detail how different stars are visible, and how the time is different in Jerusalem, over Ganges and in Purgatory, as well as how the seasons are different in the southern hemisphere. The differences between the hemispheres etc. are revisited several times to make explicit how Purgatory differs, for example in Purgatorio, canto IV, verse 55 onwards [2].
[1] http://www.italianstudies.org/comedy/Purgatorio2.htm
[2] http://www.italianstudies.org/comedy/Purgatorio4.htm