This large 11th-century castle, raised by Sancho III of Navarra and expanded by Sancho Ramírez of Aragón, broods above broad plains across which Islamic raiders once rode. Its resemblance to a crusader castle has considerable resonance with those times. Spanish-language guided tours (€1.50) are offered several times daily, or you can wander round with a self-guiding leaflet. There's plenty to see, including a Romanesque chapel and crypt, and you can climb to the upper levels of the two main towers.
The castle is a 5km drive or a 2km, one-hour, uphill walk from Loarre village.