We concluded the topic of large-scale structures in the Universe by discussing the Local Group of galaxies, of which the Milky Way is a member, and continued by exploring clusters of galaxies. The largest structures in the Universe are clusters of clusters of galaxies, known as 'superclusters'. A galaxy redshift survey conducted over many years has mapped the location and extent of superclusters out to about 2 billion light years. This map shows the presence of 'filaments' and 'voids', and informs us on the distribution of matter in the Universe at large, and helps to prove that the Big Bang was not perfectly symmetrical.