Abstract: A building formed by horizontally conjoining a plurality of congruent, self-supporting, sector-like modular building segments, each comprising a sector floor and congruent roof section, and a straight and opposing vee-shaped wall section, supported in between two opposite and converging identical rib-frames, each continuously structural and symmetrically equal about their respective planes of symmetry, therein allowing a plurality of modular building segments to interconnect on either rib-frame side to produce a variety of building configurations, one of which being a regular polygon-like building containing an interior open court. Mutually interconnected rib-frames of conjoining modular building segments, which are each approximately of bedroom-size area, fully open within their rectangular rib-frame perimeters for contiguous room expansion and for placement of various types of multifunctional demountable interior partitioning.