Refugi 307 is a large anti-aircraft shelter built in Barcelona by civilians supported by the Catalan government. It was created during the Spanish Civil War. It was supposed to be a hiding place during bomb attacks. It is the best preserved object of this type in the city. Today it belongs to the Barcelona History Museum and has been opened to the public.
The shelter has 3 entrances and a network of tunnels with a total length of 200 meters and a height of over 2 meters. There were several rooms in it for various purposes, including room for nurses, children's room and toilets.
After the armed conflict, the tunnels remained open to the city's residents. They were used by them for various purposes, including cultivation of edible mushrooms, a glassworks warehouse was also organized.