The issue of vacancy in commercial real estate is becoming increasingly significant. Particularly in certain metropolitan areas, this problem poses one of the major challenges of our time for investors and landlords. The available data on this issue is, however, limited. Objective decisions are hardly possible based on the data at hand. Publications report vacancy rates that vary significantly by region, but all should be viewed with caution, as even within the same region, there can be enormous discrepancies in the statistics. Different figures are reported even within a single city. For example, in Berlin, estimates range from 60,000 to 160,000 vacant apartments. What accounts for such varying numbers?.