In the context of Spanish public holidays, September 11th is not a national bank holiday. The date is officially recognized as a public holiday exclusively within the autonomous community of Catalonia. The phrase itself functions as a proper noun phrase, with "holiday" as the core noun, modified by the date ("11 September") and location ("Spain"), to identify a specific event whose scope is regional, not national.
This date marks the National Day of Catalonia, known as the Diada Nacional de Catalunya. It commemorates the fall of Barcelona during the War of the Spanish Succession in 1714 and the subsequent loss of Catalan institutions and laws. Spain's system of public holidays is decentralized, comprising national holidays observed nationwide, regional holidays specific to each of the 17 autonomous communities, and local holidays designated by individual municipalities. The Diada falls into the category of a regional holiday, a day of significant cultural and political importance for Catalonia, often characterized by demonstrations, concerts, and official institutional events.
Consequently, the practical application is that on September 11th, banks, government offices, schools, and many businesses will be closed within the geographical boundaries of Catalonia. However, in the rest of Spain, it is a regular working day with all services and businesses operating on a normal schedule. Therefore, understanding the regional nature of this holiday is crucial for travel, business, or administrative planning within the country.
