If you want to learn about the history of Gran Canaria and its aboriginal inhabitants (the guanches), this is a must-see. The videos will show you a lot of information about the islands in pre-colonial times and the Castillian conquest. The caves are well preserved and show you what it was like to live here, hundreds of years ago.
The entrance fee is €6 and tickets can be bought online or at the museum (card only). Their openings hours are depending on low- high season so best to check their website.