The “Marcha Real” is the national anthem of Spain. It is one of only four national anthems in the world, along with those of Bosnia and Herzegovina, San Marino, and Kosovo — that have no official lyrics. Although it had lyrics in the past, they are no longer used.
The Spanish national anthem was first printed in a document dated 1761 and entitled Libro de la Ordenanza de los Toques de Pífanos y Tambores que se tocan nuevamente en la Ynfantª Española (Book of the Ordinance of Newly Played Military Fife and Drum Calls by The Spanish Infantry), by Manuel de Espinosa. There, it is entitled “La Marcha Granadera” (March of the Grenadiers). According to the document, Manuel de Espinosa de los Monteros is the composer.
The current official version of “Marcha Real”, as described in Royal Decree 1560/1997, is a sixteen-bar long phrase, divided into two sections, each one made up of four repeated bars (AABB form).
Though the Marcha Real has no official lyrics, words have been written and used for it in the past. One version was used during Alfonso XIII’s reign and another during the Francoist State; however, none of them were ever made official. The national anthem has been played without words since 1978 when lyrics that had been approved by General Franco were abandoned.
According to Wikipedia