 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.A Jewish community in Spandau existed since the 13th century, a synagogue is documented since 1342.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.