12th October is a national holiday in Spain. It is also Saint Day for anyone called Pilar. Nuestra Señora del Pilar is the Patron Saint of Zaragoza.
The origins of this celebration go back to 1913. Faustino Rodriguez San Pedro (a wealthy and influential Spanish business man and lawyer and at that time Chairman of an organization called the Iberoamerican Union) proposed that day (which was already a festival in many South American countries and in Zaragoza) be called Fiesta de la Raza – literally Festival of the Race, and be celebrated throughout Spain and Latin America. La Fiesta de la Raza duly became an official national holiday in 1918 in Spain and some American countries, where the 12th October was already a national holiday, started calling their national day Fiesta de la Raza too.
In 1926 a Spanish priest, Zacarias de Vizcarra, displaying a little more sensitivity and respect for the diversity and wealth of Central and South American culture and race, wrote an article in which he said that the word “Hispanidad” ought to substitute the word “Race” in the official description of the 12th October festivals. The idea started to catch on, and in 1935 the national holiday in Spain was officially renamed Fiesta de la Hispanidad.
Spanish site about El Día De La Hispanidad (from Wikipedia)