The colorful, globally recognized plastic building block from the Danish toy manufacturer LEGO is a key fossil of contemporary material culture. As early as 1964, Der Spiegel wrote: "Never before has there been a toy that has been given such a wide space in the windows and shelves of toy stores and a preferred place in children's playrooms in such a short time." This study brings LEGO into the focus of folklore and comparative cultural studies for the first time. The foundation for this is to define play culture as a field of cultural research, discuss terminology, and develop research questions from it. Building on this, the study examines the LEGO building system in terms of its history and the thematic development of independent worlds. Finally, it illustrates the cultural values associated with this toy, the paradigm shifts in the cultural category of play that can be observed through LEGO, and how the building block became a central motif of contemporary everyday culture. The aim of this work is to bring the "homo ludens" and play as a phenomenon of everyday culture more prominently into the focus of folklore studies.