Alcázar de San Juan is a town and municipality in the province of Ciudad Real, part of the autonomous community of Castile-La Mancha, Spain. It is located in the plain of La Mancha.

Main sights include:

• Old windmills
• Tower of the Grand Prior (14th century)
• Church of St. Mary Major (13th-15th centuries)
• Church of St. Francis of Assisi (14th-15th centuries)
• Convent of St. Claire (16th century)