The December Carnival Activity · Alcázar de San Juan, La Mancha, Ciudad Real Image of Alcázar de San Juan, not of the place itself. The carnival of Alcázar de San Juan is celebrated between 26 and 28 December, an unusual date that makes it the last carnival of the year in Spain and sets it apart from any other Spanish carnival. In 2018 it was declared Fiesta de Interés Turístico Nacional (a festival of national tourist interest). 26 al 28 de diciembre Photo: Antonio García (CC BY-SA 3.0) What to see and do in Alcázar de San Juan