Abstract: A portable and collapsible building structure including a floor, a pair of side walls, a roof and a pair of end walls. The side walls each include a lower and upper panel pivotally coupled at their inner edges by a first hinge assembly. The outer edges of the side walls are pivotally coupled to the floor and roof by a second hinge assembly. The end walls are pivotally coupled to the roof by a third hinge assembly and releasably coupled to the floor and side walls by a C-shaped coupling chip. The first, second and third hinge assemblies permit the building structure to collapse so that the upper and lower panels of each side wall lie substantially flat between the floor and the roof, while the end walls pivot 270.degree. so as to lie substantially flat upon the roof. The first, second and third hinge assemblies include a plurality of one-piece, extruded, coupling channels, a plurality of hinge inserts, at least one hinge pin, and a C-shaped coupling clip.