On the map (m key), brownish buildings can't be entered while grey buildings can be entered (at some point or always).
This helps.
FAQ (micro): A tip about the color of buildings on the maps!
Re: A tip about the color of building on the maps!
Also because they arent named (which i do like) its handy to find a phonebooth (must be set 100yrs ago!) and read the directory.
Particularly handy for the visions mish where some places arent grey, but they are still important
Particularly handy for the visions mish where some places arent grey, but they are still important