When you go to Sax, you can have your very own set of keys to the Castle!!
Visit is free, but you must get the keys from the local police. They will hold your passport until you return the keys. Only one person of the group needs to give their passport.
Police station is located at - Calle Maestro Vives, 10
If the police are not at the office, call the number (+34676486535) and they will stop by.
The Castle itself has a few historical placards that give its history. But the views are nice and the area quite tranquil. If you plan ahead, it would be a great place to bring a picnic lunch.
There is a train station in Sax.
From Alicante, it is approximately a 30 minute ride.
From Valencia, it is approximately a 90 minute ride.
To or from any other destination, it would be best if you make a transfer in these either of these two cities, otherwise you will be on the slow, regional train and have limited routing.
If you visit the Renfe website, you will not find Sax in the pre-populated drop-down list of stations since it is so small, but you can manually select it by typing it in the "find all stations" link.