We had a three and a half hour rock tour. Ask for the extended tour as you see a bit more. It was reasonably priced and very informative. We just joined up with two other families at the port entrance and got in a taxi there and then. We saw the monkeys (our driver was really experienced and even let us hold one in our arms), the siege tunnels, the 100 ton gun, moorish castle, st michaels cave. We had a quick look in the shops on the way back, but did not get that excited about seeing mainly English shops and got back on the ship!