Cölln on the Fischerinsel is first mentioned in a 1237 document, and Berlin, across the Spree in what is now called the Nikolaiviertel, is referenced in a document from 1244.During the 15th century, his successors established Berlin-Cölln as capital of the margraviate, and subsequent members of the Hohenzollern family ruled in Berlin until 1918, first as electors of Brandenburg, then as kings of Prussia, and eventually as German emperors.Albert Einstein rose to public prominence during his years in Berlin, being awarded the Nobel Prize for Physics in 1921.In 1933, Adolf Hitler and the Nazi Party came to power.After World War II and its subsequent occupation by the victorious countries, the city was divided; East Berlin was declared capital of East Germany, while West Berlin became a de facto West German exclave, surrounded by the Berlin Wall (1961–1989) and East German territory.Significant industries also include IT, pharmaceuticals, biomedical engineering, clean tech, biotechnology, construction and electronics.Located in northeastern Germany on the banks of the rivers Spree and Havel, it is the centre of the Berlin-Brandenburg Metropolitan Region, which has roughly 6 million residents from more than 180 nations.Berlin became the capital of the Margraviate of Brandenburg (1417–1701), the Kingdom of Prussia (1701–1918), the German Empire (1871–1918), the Weimar Republic (1919–1933) and the Third Reich (1933–1945).
In 1920, the Greater Berlin Act incorporated dozens of suburban cities, villages and estates around Berlin into an expanded city.
Spandau is first mentioned in 1197 and Köpenick in 1209, although these areas did not join Berlin until 1920.
The central part of Berlin can be traced back to two towns.
In 1443, Frederick II Irontooth started the construction of a new royal palace in the twin city Berlin-Cölln.
The protests of the town citizens against the building culminated in 1448, in the "Berlin Indignation" ("Berliner Unwille").