How do I create a selection group?

I know there is a “GROUP from SELECTION” feature in blender, but I was wondering if I could go the other way around: “SELECTION from GROUP”?

I have a building, and each wall is a separate object so I can conveniently work on their materials separately. However, everytime I want to select all the walls together I have to individually click on each one. Is there a way I can basically say “select this group”?

set up a group by selecting your object and type Ctrl-G, so you can reselect it by selecting an object in the group and pressing “Shift-G >object in the same group” or “Shift-L> Same material” to select objects sharing the same material