Alcázar de San Juan is a city and municipality of Spain located in the province of Ciudad Real, autonomous community of Castilla–La Man…Alcázar de San Juan is a city and municipality of Spain located in the province of Ciudad Real, autonomous community of Castilla–La Mancha. It lies on the plain of La Mancha. From the 13th to the 19th century the history of Alcázar is strongly linked to the Grand Priory of the Order of St. John of Jerusalem. The city became a railway hub in the 19th century.