Cities have been affected, throughout History, by earthquakes, big fires, epidemics, and pandemics that sparked moments of reflection and change in the city form and public space quantity and quality. For example, this happened after the Great Fire of London (1666) or the Great Earthquake of Lisbon (1755). After episodes of destruction or disruption, debates and projects forge the urban answer to diminish future losses and risks. From this starting point, we discuss the impact of two distinct public health crisis - the epidemics of the 19th century and the current COVID-19 pandemic - on Lisbon's public spaces. For both periods, we analyze primary sources - strategies, plans, projects, and papers - designed by Lisbon City Council and that depict the ideas and tactics to tackle the urban challenges imposed by the public health crises. With this research, we discuss the impact of public health crises on public spaces policies design through two particular examples in Lisbon, from the 19th century and the current days. Furthermore, we question if these crises served, to any extent, the intentions to qualify public places and introduce a new form and image on Lisbon public spaces.

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