The long lost Capella Speciosa in Klosterneuburg was the first Gothic building in Austria. The chapel was consecrated in 1221 and was also one of the most important Early Gothic buildings in Central Europe. Research into this building has been a desideratum of art history since the 19th century. This new publication now contains a thorough analysis of all research to date. A complete analysis of those parts of the chapel, which survived the demolition by being transposed to Laxenburg, is also included for the first time. A digital reconstruction and visualisation of the building was created based on the thorough and critical analysis of these objects, and drawing also on all historical illustrations of the chapel and on the results of the excavation of the chapel’s foundations. The result is a comprehensive and scientifically authentic picture of the palace chapel of Duke Leopold VI of Austria. The advanced and innovatory, interdisciplinary research method unites art historical inventory and formal analysis with possible architectural-technical solutions