The Universe behind the Milky Way

Due to the foreground extinction of the Milky Way, galaxies appear increasi ngly fainter the closer they lie to the Galactic Equator, creating a "zone of avoidance" of about 25% in the distribution of optically visible galaxie s. A "whole-sky" map of galaxies is essential, however, for understanding t he dynamics in our local Universe, in particular the peculiar velocity of t he Local Group with respect to the Cosmic Microwave Background and velocity flow fields such as in the Great Attractor region. Various dynamically important structures behind the Milky Way have only rec ently been made "visible" through dedicated deep surveys at various wavelen gths. The wide range of observational searches (optical, near infrared, far infrared, radio and X-ray) for galaxies in the Zone of Avoidance are revie wed, including a discussion on the Limitations and selection effects of the se partly complementary approaches. The uncovered and suspected large-scale structures are summarized. Reconstruction methods of the density field in the Zone of Avoidance are described and the resulting predictions compared with observational evidence. The comparison between reconstructed density f ields and the observed galaxy distribution allow derivations of the density and biasing parameters Ohm (0) and b.