I went to this place last week and it is part of the Parco Archeologico. Maybe it was because I went out of season there were no tour guides or any that spoke English, but I wandered around the site on my own which was pleasant enough. The Ear is an interesting cave and the acoustics are amazing in there. Pigeons never sounded so frightening!
The amphitheatre which is also part of the site is also amazing, and whilst the biggest, I would say that it isnt the best as the one in Taormina which is used for shows in the summer is by far more accessible and interesting because it can be walked round.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.