I feel like I'm missing something obvious. Whenever I try to load cities I'd saved in previous game sessions, I can't find them anywhere. It's as though DOS BOX is oblivious of any actual file hierarchies my computer has, instead pretending that there's a standard array of SC2K save files, but never actually saving/writing the ones I ask it to. Can anyone teach me how to load games I've saved in the past?

Any program run inside DOSBox has no direct access to your computer's drives. It can only access the "virtual disks" as they have been mounted by DOSBox. In the case of GOG installs, the games' directories are most times mounted as C:\ directly.

I don't own SC 2000, so I cannot tell you with certainty where they are, but your saved cities should be within the CITIES directory, which is inside the directory where the game's executable is.

So, when trying to load a city within the game, they could be in C:\CITIES\ directly if GOG followed its latest trend in DOSBox installs, or inside another dir within C: (For example C:\SC2000\CITIES\).

As for finding them in your OSs file manager, make sure to look within the \cloud_saves\ dir within the directory where you installed the game (even if you don't use Galaxy). I'm not sure what you mean by that.