The cognitive map - a mental synthesis of the living environment - allows us to embed activities in a specific time and specific space. The cognitive map plays a similar role to the logic by means of which we organize meanings in an understandable way. The rules of thinking and the rules of action are symmetrical to each other: the structure of the language of space is a mirror image of the structure of everyday language. The city is therefore a collection of codes, stories and myths that have been recorded, petrified in the matter of urban formations. Paraphrasing Wittgenstein's famous formula, or perhaps narrowing it down a bit: "the limits of my language are the limits of my city." Space, like language, can organize human feelings and actions. The structure of the city implicitly contains the content shaping its inhabitants. This psychological mechanism was used programmatically by former totalitarian regimes. Mementos of totalitarianism, present in the structures of many cities, have - fortunately - lost their dark overtones, but dreams of ominous powers are still embedded in the construction of many European cities. constituting their dark matter. Modern methods of information processing allow us to reach deep into the language of space. From here it is only a step to unmasking urban myths. The article discusses some of them, implanted in the fabric of urban structures implemented in the times of national socialism. Applied mathematics has effective tools to convert these myths, opening old spaces of cities to modernity.