Environments can be quite overwhelming. (×_×) When doing a study you can pick anything that catches your eye. I usually want to identify the "main" parts of the scene, how they are spread out and where it leads my eyes.
You don't need to redraw the whole thing. You can just pick one subject. For example - Maybe there is an imposing building - what makes it look so epic ? Is it the perspective ? light ? Size of other objects ? What if you drew your own building with this perspective ? Copy, Redraw, colorpick, compare... whatever you need - to get your answers