Overview

Groß-Berlin, often written as Gross-Berlin where ß is unavailable, refers to the enlarged city created by the Prussian parliament on 27 April 1920. The law that enacted this change is commonly known as the Greater Berlin Act (Groß-Berlin-Gesetz). The statute redefined municipal boundaries and fused a number of neighbouring towns, villages and estate districts into a single urban district to better reflect the social and economic reality of the expanding metropolitan area.

The formal title of the measure was the "Law Regarding the Reconstruction of the New Local Authority of Berlin" and it came into effect on 1 October 1920. The act removed the enlarged city from the direct jurisdiction of the Province of Brandenburg and established Berlin as its own administrative district. The reform aimed to unify planning, public services, transport and taxation across areas that had already become integrated with the capital.

Territory and population changes

The new territory represented a dramatic rise in area and inhabitants. The city grew from about 66 km2 (25.5 sq mi) to roughly 883 km2 (340.9 sq mi), making it some thirteen times larger than the pre-1920 municipality. Population figures roughly doubled, rising from near 1.9 million to almost 4 million, as many residents of incorporated towns and rural suburbs became part of a single city administration.

Boroughs and incorporated towns

To manage the enlarged territory the law divided Groß-Berlin into 20 boroughs (Verwaltungsbezirke). These included central districts that had formed Alt-Berlin as well as formerly independent towns and newly defined suburban boroughs. Boroughs drawn from the old city included Mitte, Tiergarten, Wedding, Prenzlauer Berg, Kreuzberg and Friedrichshain. The seven formerly independent towns became boroughs themselves: Charlottenburg, Köpenick, Lichtenberg, Neukölln, Schöneberg, Spandau and Wilmersdorf. Additional boroughs represented larger villages or suburban clusters, including Pankow, Reinickendorf, Steglitz, Tempelhof, Treptow, Weißensee and Zehlendorf.

Administrative impact and later changes

The Greater Berlin Act was more than a boundary change: it centralized municipal functions such as housing policy, public health, transport and urban planning. By bringing urban and suburban communities under one roof, it enabled comprehensive infrastructure projects and standards that matched the needs of an industrial metropolis. The boundaries defined in 1920 largely persist today, although the political divisions shifted during the Cold War era—most notably with the division of the city and later the creation and splitting of boroughs in East Berlin during the 1970s and 1980s.

Significance and notable facts

Groß-Berlin set a precedent for metropolitan consolidation by integrating diverse settlements—industrial districts, garden suburbs and rural estates—into a single municipal framework. The law transformed civic governance, influenced urban planning in the Weimar Republic and left a territorial legacy that survives in contemporary Berlin. The reform also simplified administration around landmarks such as the Berliner Stadtschloss, whose grounds had previously been treated as a separate estate district before incorporation.

The consolidation embodied in Groß-Berlin remains a landmark in the administrative history of European cities—an early example of adapting municipal law to metropolitan growth and a foundational step toward the modern shape of Germany's capital.