Heh, that reminds me of olden Chinese earthen doughnut fort dwellings: https://en.wikipedia.org/wiki/Fujian_tulou except in greater gigantic proportions (pun on the doughnut).
Circle expansion: they could add interior and or exterior concentric circles or semi circles --but then that would complicate the simplicity, so maybe not.
Circle expansion: they could add interior and or exterior concentric circles or semi circles --but then that would complicate the simplicity, so maybe not.