Abstract: Pre-formed concrete floor slabs stacked one on top of the other, at or near ground level, are raised vertically into desired elevations for permanent attachment to the building structural columns. The same cylindrical forms used to pour each floor's height of the building's columns are also utilized as hydraulic cylinders to lift the forms, and connected floor slabs, upon the previously hardened column sections to the next higher floor level where the process is repeated until the entire building structure of columns and floors is in place.