Sui Generis
 

This is the most reconigzed spanish speaked classical rock band, and the best thing they did was an album called: pequeñas anecdotas sobre las instituciones, is the best prog album in spanish, if you enjoy prog rock in any language, this is a necesary addition to your collection, it is symphonic prog, with a little psychodelia.. it is trully amazing.
this, and the live albums were the only prog rock they made.

worth to chek out