This article is the result of research on two 'planning anomalies' in Latin America: The preservation of the city walls of Cartagena de Indias, Colombia and San Juan, Puerto Rico. Although both defensive systems are tourist icons nowadays, behind their retention lays a long history of contestation. Planning, spatial and socio-economic issues are considered in the article, which deems these processes unique and idiosyncratic, for the norm throughout the continent was to tear down walls of this type. In San Juan, a long period of military use and in Cartagena a comfortable attitude as well as an early touristification process ultimately explain the preservation of the walls. However, keeping the walls has not led to a significant difference for urban planning processes in the two cities, nor in the two cities centers, when compared to other similar cites of the region.