This summarizes a review of Rob Krier's book "Urban Spaces": Krier's book examines how the understanding of traditional urban space has been lost in modern cities. It analyzes the typological and morphological elements of urban space, including squares, streets, and how they are shaped by modulating factors. Krier illustrates how urban space has eroded over the 20th century due to factors like the demolition of city walls and the influence of industrial buildings on urban planning. He proposes approaches to redevelop cities by restoring continuity of spatial experiences and focusing on pedestrian-friendly areas.