I found some peseta notes stashed in an old book - do the banks still exchange them or are they worthless now?
The Banco de Espana used to exchange them but I'm not sure if they still do. good luck!
There is an informative page on the Banco de Espana site : https://sedeelectronica.bde.es/sede/en/menu/tramites/Canje_de_pesetas_a_euros.html
Thanks for that!