Spain's biggest festival
April
Some of Spain's biggest festivals take place during April and May starting with Holy Week
(Semana Santa) which is important nationwide but is especially recommended in Seville, Cordoba, Granada and Malaga. The celebration of Holy Week is the highlight of the year in Andalucia with teams of parish members carrying enormous religious floats.
http://www.spanish-fiestas.com/spanish-festivals/calendar.htm