What do you call a pentagon made of pentagons?

A mapping challenge!

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So the idea was to take a series of pentagons and tie them together within a pentagon and create a fortress out of it. The first draft (above) was just to hammer out some basic functional design issues. I wanted to figure out how people were able to get up and down through the many floors of the fortress so I decided that the central pentagon would be something of an open space (like a sun well) with stars. It would bring in plenty of light and, hopefully, make the inside of the fortress appear less gloomy.

Once movement was sort of figured out I thought that I would try populating the spaces with various room elements to see what happened.

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So I added a basic barbican or gatehouse to the space between two pentagons and then tried to fill in some spaces with tables for a dining hall and bookshelves for a library.

It's not...wrong but still doesn't feel right.

So then I decided that I'd take a different perspective and fool with the shape itself and see what shook loose.
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Rather than running to Google Sketchup I tried to use some of the tips on creating an isomorphic map. This gave me an idea for how the design would look once rendered into a third dimension and I started to like it more.

After duplicating the levels I ended up with something like this:
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I'm not sure if I like the straight-sided walls of this version or if it would be better to gradually decrease the size of the pentagon...florette? So that it becomes a 'stepped' fortress.

I read that stepped structures more evenly distribute the weight of the upper floors but I'm not sure if that would apply for a shape like this.

Any suggestions on the wall-sides? Stepped or straight?