‘You’ve got everything in there, haven’t you?’ said James.

‘It certainly feels that way when I have to lug it about the place,’ said Haight.

James took a drink. The water was salty and bitter.

‘Don’t be put off by the taste,’ said Haight, smiling. ‘I always use water-purifying tablets. You can’t be too careful out here.’ He took the bottle from James and replaced the stopper. ‘Now then, if you’ve had enough of digging why don’t you take yourself off and explore the tower? It’ll be nice and cool in there.’

‘Thank you, sir,’ said James. ‘I’d like that.’

‘It was bashed about a bit by the Carthaginians in the fifth century BC,’ said Haight, ‘but I think it would have taken their whole army to knock it down. Quite extraordinary. You know, they didn’t use any cement or mortar to stick the stones together. They were simply cut to shape and placed one on top of the other. The builders must have known exactly what they were doing though, because it’s still here after all this time. Have a good look inside. And the view from the top is magnificent. I’ll see you when you get back down to terra firma.’

James strolled back out into the sunlight and made his way across the site. As he neared the tower he saw that it was surrounded by a raised terrace supported by three lower towers in a triangular shape.

He found the entrance in the massive outer wall and went inside to a courtyard with a ruined well in its centre. There were doors leading off from here into the various towers. He chose one at random and passed through a circular room into the darkness on the other side. He was momentarily blind as his eyes adjusted but eventually saw that he was in a long corridor of gigantic stones whose sloping sides met at the roof. He shuffled forward. The place was confusing and utterly unlike anywhere he had ever visited before. It seemed to have walls within walls. He groped his way along in the cool darkness until he found himself in a windowless domed chamber, some 20 feet wide by 20 feet tall. This must be the heart of the monument, the base of the main tower. There was a square of dazzling white light in the doorway but very little of it penetrated this deep. He could see, though, that the black volcanic rocks were tinged with red, almost like rust and he imagined for a moment that the tower was built of iron rather than stone. It was eerily quiet and he had the weird feeling that he had travelled back in time to somewhere truly prehistoric. He felt unnerved, as if these ancient stones held the ghosts of the long-dead people who had lived here. The outside world, the modern world, seemed a long way away. A wave of sickness struck him and the room started to spin. He thought he heard voices, but it could just have been the blood roaring in his ears. He closed his eyes and rested his forehead against a wall to cool it.