Residential density and accessibility are essential aspects of urban sustainability. Well-planned cities allow people to access to services and goods in an efficient manner in relatively dense housing schemes, but how do these two aspects interact? This article investigates the inner spatial structure of the housing estates and their integration with the rest of the city. It reports the axial and visual analyses of nine housing estates located in different parts of Santiago de Chile; a city that almost eradicated severe forms of deprivation, but has socio-spatial segregation together with profound inequalities. The analysis shows that the housing estates located in disadvantaged areas have labyrinthine and highly segregated spatial structures. Conversely, the inner structures of the housing estates located in wealthy areas are, in general, well-integrated. Moreover, the comparison between the original and the current situation of the housing estates shows that the proliferation of irregular house expansions, gates and fences have reinforced frontiers and fragmented otherwise large open spaces devoted to the community. On the contrary, those housing estates that are in well-off areas have, to a great extent, preserved their structures over time. The findings indicates that the fragmentation and the spatial arrangement observed in the housing estates located in disadvantaged areas may strengthen the dichotomy between the interior and the exterior, fuelling the—already high—perception of insecurity in Santiago. Furthermore, the contrasting trajectory of the housing estates according to their socioeconomic background suggests that the existing schemes to “densify” underprivileged areas need to be redressed.