In the 1970s, the East German government had large pre-fabricated high-rise housing estates (Plattenbau) built in the east of the Lichtenberg borough. This area was separated off and became the new borough of Marzahn, which included Biesdorf, Hellersdorf, Kaulsdorf and Mahlsdorf in 1979. In 1986, this district in turn was split into the two boroughs of Marzahn and Hellersdorf in 1986, and again merged as Marzahn-Hellersdorf by the 2001 administrative reform.