The present invention resides in an improved modular building structure (100) comprising a collapsible structural frame (200) comprising a 5 roof frame (400) and a base frame (300) detachably connectable via at least one removable column (500) and plurality of interchangeable external wall panels (600) attachable to the structural frame (200). In a collapsed state, the at least one removable column (500) is accommodated in a space (160) between the roof frame (400) and the adjacent base frame (300). 1187163v1
