Vectorworks 2010 and 2011 have a wall editing concept called Wall Sculpting. This allows you to create projections and cut-outs in walls. When you look at the plan of the old building, there are old fireplaces, different wall constructions and old blind windows.
If you have an older version of Vectorworks, you can not use Wall Sculpting, so you will have to use walls or walls and pillars. Pillars don’t work as well as walls, because you can not insert a door or window into a pillar.