The Air Raid Shelter at Plaza Tetuán is an underground construction built between 1937 and 1938, during the Spanish Civil War, with the objective of protecting the civilian population of Castellón from aerial bombardment. Its location beneath Plaza Tetuán, in the heart of the city's historic centre, responded to the need to provide shelter in a central and easily accessible location.

The shelter is part of a network of defensive infrastructure constructed in many Republican cities during the conflict. Castellón suffered numerous air attacks throughout the war, making these installations vital elements for the daily survival of its inhabitants.

After decades of neglect, Castellón's town council promoted a project to recover and rehabilitate the shelter, which was inaugurated as a museum and historical interpretation space. It currently forms part of the headquarters of MUCC (Museu de la Ciutat de Castelló), with free entry and guided tours available in Spanish, Valencian, English and French.

Access to the shelter is via Plaza Tetuán itself. Free visiting hours are Tuesday to Saturday from 16:00 to 19:00, and Sundays and public holidays from 10:00 to 14:00. It remains closed on Mondays. Capacity is limited to 60 people and guided tours are offered for groups by prior booking.

A notable aspect is the availability of a downloadable audioguide in four languages, as well as specific information materials on the space's accessibility conditions, which demonstrates MUCC's effort to make this historical heritage accessible to all audiences.