The Cross radiotelescope at the Molonglo Radio Observatory (Mills et al. 1963) came into full operation during 1967 and observations continued without interruption until 1978 when it was closed down for substantial modifications; these are now largely complete and observations have re-commenced. The decision to make some drastic changes was taken about seven years ago, although it had been evident right from the beginning that scientific returns from the Cross would drop sharply once the whole accessible sky had been surveyed. Indeed, the specifications for the original instrument were chosen to permit a subsequent conversion from 408 MHz to 1420 MHz with little extra expenditure on the reflector structure. Also, in 1972 a new form of circular polarized antenna was developed to provide a cheap mass-produced feed for 1420 MHz operation which could be easily phased and had good directional properties (Mills and Little 1972).