Abstract: A multi-floor building of the kind in which floors are suspended from a central support has a support core with a plurality of vertically spaced and horizontally aligned openings for individual floor support beams. The building floors are built at ground level and lifted to the desired height on the support core. Floor support beams are inserted through horizontally aligned openings in the support core between the floor. The floor is then set on the support beams to support the floor at that level directly from the core and independently of all the other floors of the building.The system uses jack rod support beams on top of the support core. Jack rods are connected down from the jack rod support beams, and lifting jacks jack up the jack rods to lift each floor to the desired level.A conveyor beam lifts each support beam to a position in which the support beam can be inserted through the openings. A removable winch carried on the floor pulls the support beam through the openings in the side walls.