Hellersdorf is a locality in the borough of Marzahn-Hellersdorf in Berlin. Between 1986 and Berlin's 2001 administrative reform, it was a borough in its own right, consisting of the current area of Hellersdorf as well as Kaulsdorf and Mahlsdorf. Before German reunification in 1989 it was part of East Berlin. Situated at the eastern rim of Berlin the area is mainly a large housing estate from the 1980s, made up of Plattenbau (concrete slab) buildings.