I couldn't help myself. I had to throw this into sketchup and get some sense of scale.
Basic theme has been replicated and I like the look of it.
But I had no idea how big the walls would have to be to accommodate the design.
Originally the idea was to have the entrance between two of the pentagonal shapes. To accomplish this I used the scale tool and kept making the whole shape larger until the tiny wall between the two sections was large enough to accommodate a proper entrance.
Based off the original design - to put an entrance in that tiny opening the structure would have 17' thick walls and they were 72' tall.
Yup... Back to the drawing board.