One of the primary strategies of slowing down the COVID-19 pandemic has been the establishment of social distancing rules that recommend keeping a buffer distance between individuals, and this has proven effective in helping in reducing the basic reproduction number [R 0] . However, social distancing rules have put the use of public spaces in densely populated places under strain, and this is especially important as some of the most virulent outbreaks of the COVID-19 pandemic have been in compact cities. It is therefore fundamental to take into account each neighbourhood's morphological characteristics and the potential population densities each street, square or park can accommodate under such new regulations in order to effectively enforce social distancing rules. Otherwise, certain areas may be rapidly overwhelmed by crowds with citizens unable to maintain the minimum safe distance between individuals. In this paper, we develop a method to identify the potential public space accessibility if social distancing rules are followed and we apply it to three global and highly affected by COVID-19 cities. Our research finds that, at micro level there are important inequalities between neighbourhoods, so people will struggle to comply with social distancing rules and consequently it will make controlling infection rates more difficult.

La consideración de los elementos que merecen una protección especial por parte de la administración pública ha ido cambiando a lo largo del tiempo. De forma progresiva se ha pasado de una visión basada en lo antiguo y monumental a una visión mucho más amplia. Este cambio se ha integrado en los últimos años en los distintos elementos legales. El texto que se presenta reflexiona sobre este hecho mediante el análisis del trabajo académico realizado para la elaboración del “Catálogo de construcciones en suelo no urbano del municipio de Lleida”, documento que formará parte de la revisión del Plan Urbanístico de la ciudad. El trabajo detalla el estudio realizado para la propuesta del Catálogo. Se partirá de una presentación de los elementos generales que establece la normativa urbanística de Cataluña. Posteriormente, se presentará el trabajo de identificación de construcciones y los criterios fijados para delimitar las construcciones que debían preservarse. Finalmente, se presentarán los principales rasgos de las aproximadamente 150 construcciones para las cuales se propone su conservación como elementos más significativos de un espacio que conserva más de 800 años de presencia humana. The consideration of the aspects that deserve special protection by the public administration has been changing over time. Progressively it has change from an ancient and monumental idea to a much broader view. This change has arrived to the urban legislation in recent years. The text presented reflects on this fact by analysing the academic work done for the development of the "Catalogue of constructions in undeveloped land in the municipality of Lleida". This document will be part of the review of the Urban Plan of the city. The paper describes the study conducted for the proposed Catalogue. We will start by a presentation of the general elements that set the planning regulations of Catalonia. Then we present the criteria set for the buildings that should be preserved. Finally, we present the main features of the approximately 150 buildings for which conservation is proposed as significant elements of a space that preserves more than 800 years of human presence.