We were asked to move along.

The Soma was just one feature of the grandiose Museion complex. A Temple to the Muses sat in a huge area of formal gardens, within which stood phenomenal buildings dedicated to the pursuit of science and the arts. It had a zoo, which we left for another day when we could bring the children. It was also home to the legendary Library and other handsome accommodation where scholars lived and ate. ‘Tax-free,’ said Helena. ‘Always an incentive to intellectuals.’ I was not yet ready to explore the seat of learning. We refreshed ourselves strolling among the shady terraces and water features, admiring the stork-like ibises who dipped their curved beaks in the elegant canals, where lotuses were in flower in brilliant blue. I plucked an opening bud to present to Helena; its scent was exquisite.

Later we strolled towards the sea. We came out at the end of the narrow causeway that linked the mainland to Pharos Island. This causeway was called the heptastadion because it was seven Greek stades long - about four thousand feet, I reckoned by eye - more than we wanted to tackle that day. From the docks on the Great or Eastern Harbour, we had a good view of the Lighthouse. When we sailed in yesterday, we had been too close to look up and see it properly. Now we could appreciate that it stood on a spur of the island, set within a decorative enclosure. Overall, it rose to about five hundred feet. The tallest man-made structure in the world, it had three storeys - an enormous square foundation, which supported an elegant octagon, which in turn held up a round lantern tower, topped off with a great statue of Poseidon. Back in Italy, the lighthouse at Ostia was built to the same pattern, but I had to concede it was no more than a feeble imitation.

Part of Pharos Island, together with the heptastadion, formed one enormous arm around the Great Harbour.