During the Spanish Civil War, L'Hospitalet suffered directly from the ravages of the bombing raids that Italian and German aircrafts, in support of the military uprising led by General Franco, carried out against the civilian population in the Republican rearguard. The bombings - 18 of which have been documented over a period of 3 years - continued until the day before Franco's troops entered L'Hospitalet, affecting several districts of the city, destroying homes and factories, causing casualties and wounded.These events are still present in the memory of many neighbours who experienced them first-hand or have heard the stories from their parents and grandparents. Some traces of the bombings, such as the air-raid shelters built in the period 1937-1939, are also still present and hidden. In the face of the air raids, society answered: both the institutions, with the constitution of the Passive Defence Board, and the neighbourhood, organised to build air raid shelters to protect themselves from the bombs. Thus, the air-raid shelters can be considered as one more material representation of the act of war.This route will lead us to discover some of the air raid shelters located in the neighbourhoods of Collblanc, la Torrassa, Sant Josep and the Centre. This is a selection of the total of 39 air raid shelters that are known in L'Hospitalet and will allow us to discover its typology, as well as the context in which they were built. These sites were the heart of the city, the centre with the highest concentration of population and industry in the years between 1936-1939. Moreover, we must add the marked anti-fascist character of L'Hospitalet, where the political forces opposed to the coup d’état held hegemony in some areas, as would be the case of the CNT-FAI in Collblanc-La Torrassa. This combination of factors meant that these parts of the city were sensitive targets for fascist aircraft and, as a result, in these areas most of the passive defence structures were set up to protect citizens from bombs. In fact, beyond the geographical triangle formed by the aforementioned neighbourhoods, there is no record that the local Passive Defence Board planned the construction of shelters in this "peripheral" area. Therefore, all the air raid shelters that have been documented outside this 'triangle' were all homemade.The air-raid shelters are the common thread that will help us to reflect on the essential aspects of the resistance and passive defence of the citizens of L'Hospitalet, including the casuistry of the most affected working-class neighbourhoods, as well as the different forms of social organisation in the face of the conflict. They are physical traces of the Spanish Civil War in our city and, therefore, they are part of the cultural heritage of L'Hospitalet. Keeping their memory alive means making the everyday life of the war visible and, at the same time, raising awareness of its horrors and, unfortunately, of its terrible relevance in the most recent war conflicts. It is difficult to determine the exact number of bomb shelters that were built in L'Hospitalet during the civil war. Some structures excavated in slopes or in the subsoil of buildings, such as basements, were reused and adapted to take refuge from aerial bombardment. The map of shelters in Hospitalet shows a wide constructive typology.Documentary references and archaeological evidence collected to date confirm the existence of twenty (20) structures used as anti-aircraft shelters. However, there are indications of twenty more locations that, at this time, have not been confirmed.The appearance of new documents in January 2023 confirmed the existence of some shelters of which there were only indications and revealed some important details regarding the construction process and the local historical context. We show on the 1938 city map the location of 20 (twenty) structures used as anti-aircraft shelters. We observe the following distribution: 14 in Collblanc-la Torrassa, 1 in Sta. Eulàlia, 1 in Sanfeliu, 3 in Centro-San José and 1 in Florida-Pubilla Casas. Shall we start?