Beyond the anthropological understanding of liminality, it's gotten an interesting focus in the architecture discipline. Architects, often phenomenologists, focus on Turner's "betwixt and between" spaces: designed spaces that are boundaries. The most common liminal spaces focused on are the designs of vestibules, stairs, entryways, circulation, porches/balconies, and material transparency. I think the designing of liminal spaces is so common due to the lack of rigidity to its function. People sit on stairs and sing from balconies. The openness of function allows for spontaneity