This castle is not located incredibly close to a village, so the recommended way to get there is to rent a car or maybe hitchhike. There is parking space available next to the road at the foot of the mountain, near the river. The fortress itself is accessible by climbing close to 1500 steps!
To get to the castle by car, essentially drive north on National Road 7C past the few small villages until you hit the hydroelectric power plant. Then, look up! You can't miss it.