The metropolis as a monument: This volume on the area of Vienna's city center is part of the first comprehensive on-site inventory of monuments in the city of Vienna, the historically continuous center of Central Europe. As in all previously published volumes of the new Dehio series, a directory has been created here based on topographical and systematic comprehensive surveys, listing all monument-relevant objects and attempting to present them in their context within the extremely compact urban structure. With the publication of Volume 1 on the Vienna city center, the Vienna series is completed following the release of Volume 2 on the former suburbs of Vienna (1993) and Volume 3 on the former outskirts of Vienna (1996). Vienna, an architectural ensemble of the highest international standing, thus possesses a unique comprehensive inventory of a European metropolis. Specifically, the historical heart of the million-inhabitant city is characterized by its millennia-old settlement structures, such as the high density and extraordinary quality of its architectural and artistic substance. In 2001, Vienna, with its center, was designated a UNESCO World Heritage Site, extending from the core zone far into the suburbs. In addition to globally significant individual monuments, foremost among them St. Stephen's Cathedral and the Hofburg, the dense construction of churches, monasteries, palaces, public monumental buildings, and residential houses impresses, as does the range of medieval and modern styles. The abundance of monuments, outdoor sculptures, and fountains, along with extensive parks and gardens, enriches the diversity of the cultural heritage, as do facilities for transportation and technology. Plans and floor plans of the most important buildings and facilities illustrate and complement the texts, while an overview map traces the development of the Vienna city center. The detailed indexes facilitate the retrieval of numerous pieces of detailed information.