You build a castle on a hill for a reason: to spot your enemies and defeat them in 13th-century Spain. Yedra Castle still overlooks the walled city of Cazorla. You half expect a princess to lean out of a window and armor-clad knights to descend the steps. Today, Yedra marks the entry point to a wild region of river gorges and forests that now host nature lovers seeking a peaceful escape from the modern world.