It’s a well-kept secret: Nobody knows exactly how many apartments in Vienna are actually empty. Estimates put the number at around 100,000 residential units – enough that the city would not have to create new housing for seven to ten years. This is what representatives of the Chamber of Civil Engineers and Architects calculated, who recently invited people to an excursion and discussion. This clearly showed how different the Viennese parties stand on the issue of mobilizing vacancies.