I'm having a bit of a disagreement of the use of the Highlord's Mark ability.
At 5th level, willingly or unwillingly, a highlord’s charismatic and psionic nature bleeds into the environment around him. The highlord can establish a location as his territory, after spending at least a week in the area around it. This location must be an area no larger in volume than a cube that is a number of feet per side equal to 10 feet per highlord level. If it is a public (or at least well known) area, it becomes widely regarded by others that the highlord controls or own it in some way. The highlord’s power influences the appearance of the area through his open heart ability, though objects within it are not changed as to become unrecognizable.
My opinion is that you can spread out the area provided by the ability to cover irregularly-sized areas, or restrict it so that it only covers a single building, due to the very specific "area no larger in volume than a cube that is..." wording.
One of my fellow players believes that it's an immutable cube. So if you're a level 5 Highlord, you get a 50x50x50 cube and just plop is down somewhere. For example, if there's a tower that's 20x20x60, you have to wait until level 6 to fully claim it.