The idea is this: draw a map of a place that calls to mind a place that actually exists or existed, but it is a different version of it.

So you could draw a fantasy version of your country or a map showing the district where you live in a thousand years in the future or what would have happened if Mordor had prevailed, or what would have happened if there had been steam engines in ancient Greece; I think the theme is vast and could provide countless possibilities (uchronic, fantasy and sci – fi maps and mix and variations of tropes and genres would all be possible) and it would be a challenge whose guidelines would be not so strict (good or bad thing, I realize, depending on your point of view; but stricter guidelines could be imposed).