The Universidad Carlos III de Madrid (UC3M) is listed as one of the best Spanish institutions to study a postgraduate degree, according to the new 250 MASTERS ranking published by the newspaper El Mundo in their sixteenth edition. According to the results of this report, the UC3M has 21 masters in the five top positions among the 50 specialities that are evaluated.
More info here: https://www.elmundo.es/especiales/mejores-masters/