Interstitial space is a multifaceted architectural concept describing areas situated between clearly defined functional rooms. It can manifest physically as a corridor, buffer zone, or technical service space, or conceptually as a transitional zone between interior and exterior, or between public and private realms. Architects such as Aldo van Eyck and Herman Hertzberger paid particular attention to interstitial space, understanding it as a social stage. In urban planning, such spaces often arise unintentionally between buildings and infrastructure elements. They offer potential for informal appropriation, greening, or new uses. The conscious design of interstitial spaces is considered a hallmark of high-quality, human-centred architecture.