The Sloan Great Wall was first identified in 2003 as part of the Sloan Digital Sky Survey, and is probably the largest structure in the known Universe. It is around 420 Mpc (c. 1.4 billion light years) long, and around 300 Mpc away, though estimates do vary. Some parts of it are not gravitationally bound together and and may never be, so in some ways, we should not really consider it as a single coherent structure. Nevertheless, it is impressive. Shown in the image to the left with the Shapley Supercluster, and parts of the Pisces-Cetus filament and Horologium-Reticulum Supercluster.
