The Cervantes Institute, which promotes Spanish language and culture, said it held open days at its 73 branches "to increase the visibility of the Spanish language in the world."
At the institute's headquarters in Madrid, the day was officially launched when a compressed air cannon blasted out thousands of bits of coloured paper into the street with Spanish words on them.
In addition, concerts, films, storytellings and children's workshops were held throughout the day.
The Cervantes Institute, named after Spain's most celebrated writer, Miguel de Cervantes, plans to hold the Spanish Day every year on the Saturday closest to the summer solstice.
It has also launched an interactive website, www.eldiae.es to promote it.
