Castell del Rei is located 7 km north of Pollenca and it is reachable only by hiking. Anyway, this hike to this remote mountain castle is one of the loveliest in Mallorca.
Bad news are that Castlell del Rei is on a large private estate and you have to apply for permission at the Town Hall in Pollenca to get access. This permission can take up to four days to be granted. You can arrange permission online via Pollenca Town Hall. Notice that cars are not allowed so excursion must be on foot. Walk from Pollenca to avoid parking problems and allow at least five hours for the round trip.
Castell del Rei was founded by the Moors and strengthened by Jaume I. Castell del Reihas been abandoned since 1715 and is rather romantic if you manage to be there by yourselves. Take some food and enjoy a picnic with a spectacular view.