If something should happen to your building, for example you ruin a wall when modifying it or it suddenly is returned to your inventory by some reason, it’s easy to rez a new building and place it on the same location, using coordinates. Especially if you have filled the building with furniture’s.
When you have found the perfect for your building, make a note of the coordinates of the REZ BOX (not the building itself). The X, Y and Z coordinates can be found in the edit menu under the OBJECT tab. Make sure you are on the MOVE selection in the edit menu and make a note of the position values highlighted in colors: Position (meters) the values X, Y and Z. The same values can be entered later in the Edit Mode of your Rez box to position your building exactly at the same spot as your previous building.