Picture XIX Solution: http://www.jerrybarton.eu/Architecture/DoYouKnowVienna/28990687_zwRPWb#!i=2481109456&k=32BGMjj
Picture XX Solution: http://www.jerrybarton.eu/Architecture/DoYouKnowVienna/28990687_zwRPWb#!i=2481108647&k=6qXZFT2
Picture XXI Solution: http://www.jerrybarton.eu/Architecture/DoYouKnowVienna/28990687_zwRPWb#!i=2481180126&k=KDBVjxt