The addition of some 1x2 bricks in the inner spaces would make the structure even more stable. If built all in one color, it would make an interesting tower for a castle, I would think.
With the 1x2 bricks added, the structure is easily stable enoungh to put on its side. In fact, I built three of these things, with differing colors and heights, and connected them all with 2x6 bricks. Set on its side, it ended up looking a bit like a set out of a science fiction movie, and the rendering of this via POV-Ray is a future project.
(Again, many thanks to Steve Bliss for providing a valuable insight, and to all the people who have contributed to the parts libraries available on the 'net.)
