A castle at Spandowe, erected on a Havel island to secure the eastern borderlands of the Margraviate of Brandenburg, was already documented in an 1197 deed issued by the Ascanian margrave Otto II.
The city itself was first mentioned on 7 March 1232, when the Spandau citizens were vested with further privileges by the Brandenburg margraves John I and Otto III.
It became the initial point of the Protestant Reformation in Brandenburg, when on 1 November 1539 Elector Joachim II Hector converted to Lutheranism and celebrated the first communion under both kinds here.
The Hohenzollern elector also had the city protected from attacks by the Spandau Citadel, a Renaissance fortress erected at the site of the medieval castle from about 1560 onwards.
[1] The walled-up Altstadt quarter became the nucleus of the larger Spandau Fortress, built under Prussian rule after the Napoleonic Wars in the early 19th century, also a centre of the German arms industry.