A method is disclosed for optically pre-aligning and referencing an antenna set-up outside an antenna measurement range. The pre-alignment is performed in an integration room close to the antenna measurement range in order to avoid unnecessary occupation of the measurement range. The method teaches a technique using generally a pair of high accuracy theodolites (T1, T2) to by means of a room mirror reference (RM) and an antenna mirror-cube transfer a difference between the co-ordinate system of an integration tower (INT) used and the measurement range antenna tower.