CfA2 Great Wall
The Great Wall (also called Coma Wall), sometimes specifically referred to as the CfA2 Great Wall, is one of the largest known super-structures in the Universe (the largest two being the Sloan Great Wall and the Pisces-Cetus Supercluster Complex). It is a filament of galaxies approximately 200 million light-years away and has dimensions which measure over 500 million light-years long, 300 million light-years wide and 15 million light-years thick, and includes the Hercules Superclusters, the Coma Supercluster and the Leo Cluster.
It is thought that dark matter dictates the structure of the Universe on this scales. Dark matter gravitationally attracts baryonic matter, and it is this "normal" matter that astronomers see forming long, thin walls of super-galactic clusters.
