This book explores the relationship between architecture and philosophy through a discussion on threshold spaces linking public space with publicly accessible buildings. It explores the connection between exterior and interior and how this creates and affects interactions between people and the social dynamics of the city. Building on an existing body of literature, the book engages with critical philosophy and discusses how it can be applied to architecture. In a similar vein to Walter Benjamin's descriptions of the Parisian Arcades in the nineteenth century, the book identifies the conditions under which thresholds reveal and impact social life. It utilises a wide range of illustrated international case studies from architects in Japan, Norway, Finland, France, Portugal, Italy, the USA, Australia, Mexico, and Brazil. Within the examples, thresholds become enhancers of social interactions and highlight broader socio-political contexts in public and private space. Architecture of Threshold Spaces is an enlightening contribution to knowledge on contemporary architecture, politics and philosophy for students, academics, and architects.