  Hubble's announcement of the magnitude-redshift relation \cite{Hub29} brought
about a major change in our understanding of the Universe. After tracing the
pre-history of Hubble's work, and the hiatus in our understanding which his
underestimate of distances led to, this review focuses on the development and
success of our understanding of the expanding universe up to the present day,
and the part which General Relativity plays in that success.
