(b Siegen, 2 Aug 1898; d Düsseldorf, 20 Jan 1987). German architect. He studied architecture at the Kunstgewerbeschule in Munich (1919–23). From 1923 he worked as an assistant architect in Augsburg and Berlin, working independently from 1930 and becoming District Architect at Sonthofen in 1933. The following year construction of the Ordensburg Sonthofen began, his first commission for the National Socialist party. The design of the building followed historical models, medieval castles and monasteries, and it was constructed following the regionally specific forms of Heimatschutzarchitektur. More commissions for the Nazis soon followed, including designs for Gauforums (Nazi assembly and parade grounds) in Weimar and Augsburg, and the plans for the Hohe Schule of the NSDAP on the Chiemsee. With these buildings and projects Giesler established himself as a designer of large, integrated sites, and in 1938 he was appointed Chief of Planning for the Capital City of the Movement by an edict of Adolf Hitler, working directly under his command.