Quseir Amra is a well-preserved desert castle which acted as both a fortress with a garrison and a residence of the Umayyad caliphs, built in the early 8th century.
El Castillo de Buen Amor (the Castle of Good Love) may be about the least martial name ever conceived for a fortress, but in truth this place in the plains north of Salamanca was designed more for pleasure, despite its crenellations, impressively bulky walls and (dry) moat.