For everybody who is interested in archaeology this is a must. The history of the site is so interesting and dates back to paleolithic times. Due to volcanic activity there used to be a lot of carbon dioxide lakes nearby the cave. These lakes were magical to the first inhabitants of the area and it continued to be a religous centre in the next millenia. There is evidence of Sucili, Greek, Roman and Arab activity.
It is a bit out of the way and you'll probably need your own wheels to get there but it is definitly worth it. The small museum holds some real gems. And if you're there when they are excavating the workmen are so proud of their site it might be impossible to shut them up...