Most clusters tend to be part of a larger grouping called a supercluster. The local group is part of a larger supercluster called the Virgo cluster. This massive cluster contains over 2000 member galaxies. As astronomers begin to map the locations of these galaxies, a grand structure is beginning to take shape. What once appeared to be a random distribution of galaxies is now revealing itself to be a complicated design.
Galaxies seem to be grouped together in what appears to be a very complex sponge-like arrangement.
The large galactic superclusters are gathered around what appears to be giant voids or bubbles. Nobody knows why this structure exists. We also do not know what, if anything, might exist inside these voids. They could be largely composed empty space or they could be filled with some type of exotic dark matter. It may be some time before we can fully understand the mechanics behind this grand design.