This question can be well answered with the database of Skyscraperpage on
https://skyscraperpage.com/diagrams/ . However here is the answer:
the tallest building in Spain isTorre de Cristal in Madrid with a height of 249 metres.
However there are some radio towers and chimneys with greater height and the tallest man-made structure in Spain, is the Torreta de Guardamar, a 370 metres tall radio mast of the Spanish Navy in Guardamar del Segura.