A positioning aid for aligning a heavy machine is fitted to the underside of the heavy machine and is to be brought as desired into contact with a base support or floor. The positioning aid includes at least one aligning element for floatingly mounting the heavy machine in one plane when the positioning aid contacts the floor. A heavy heavy machine has a first movement system and the positioning aid. A method of aligning a heavy machine with a first movement system and a positioning aid includes coarsely positioning the heavy machine with the first movement system on a floor. The positioning aid is extended, so that the first movement system loses contact with the floor and is then floatingly mounted. The heavy machine is freely rotated and displaced on the positioning aid. The heavy machine is lowered onto immovable adjustable feet when reaching the desired position of the machine.