Maps of the galaxy distribution in the nearby universe reveal large coherent structures. The extent of the largest features is limited only by the size of the survey. Voids with a density typically 20 percent of the mean and with diameters of 5000 km s-1 are present in every surgery large enough to contain them. Many galaxies lie in thin sheet-like structures. The largest sheet detected so far is the ``Great Wall'' with a minimum extent of 60 h-1 Mpc × 170 h-1 Mpc, where h is the Hubble constant in units of 100 km s-1 Mpc-1 The frequent occurrence of these structures is one of several serious challenges to our current understanding of the origin and evolution of the large-scale distribution of matter in the universe.