How do they decide what exactly cannot be lost in an old building during renovation and restoration? The lecture will explain how state control works in the field of heritage and what is hidden behind the concept of "subject of protection" - from facade details to historical layouts. The lecture will explore how the state controls the preservation of cultural heritage sites. The main topic will be the "subject of protection" - a legally established set of characteristics that grants the monument a special status. This can include architectural details, layouts, structural features, materials, decorative elements, and the building's connection to historical events or people. We will discuss how to organize leisure in St. Petersburg.