Onda Castle is a 10th-century Muslim fortress built on the ruins of an ancient Roman settlement. Known as the "castle of 300 towers" due to its immense size, it occupies an unbeatable strategic position between the La Plana plain and the Sierra de Espadán mountain range. In 1250, it was transferred to the Knights Templar, and later, in 1319, it passed into the hands of the Order of Montesa. The castle currently houses a museum and is open to visitors year-round.