Abstract: A portable building structure is provided with a central main frame with a roof and a floor and pair of spaced apart uprights located at each end of the main frame creating an recess, top and bottom of the main frame, at least one movable roof structure mounted relative to the recess for movement between a raised, use position and a folded, storage position in which the at least one movable roof structure at least partially closes a lateral side of the main frame, at least one movable floor structure mounted relative to the recess for movement between a lowered, use position and a folded, storage position and at least one moveable wall structure including an end wall frame and a pair of folding frame walls, one at each end of the main frame, mounted relative to the recess, a second of each pair mounted to the end support, for sliding movement from a storage position within the recess, to a use position between an outer end of the at least one movable roof structure and at least one movable floor structure whe