The water at the entrance to Alexandria harbour was being stirred up by divers exploring the sea bed. I could only see their bubbles breaking the surface of the grey-green mucky-looking water, but from time to time they surfaced with reports of more large pieces of ancient masonry strewn all over the bottom.
It was built by Ptolomy II, soon after Alexander the Great founded his Greek capital at the mouth of the Nile in 332 BC.
And archaeologists believe that what they are finding under the water is the tumbled remains of that lighthouse - an enormous building about 60 metres high - which had been destroyed by earthquakes in the Middle Ages.
Book lovers
It has always been understood that the fortress on the shore overlooking the harbour, and built by a Muslim ruler in the 16th Century, was largely built of masonry from the lighthouse. I was shown some of the lower courses by archaeologists who are sure that some of the big blocks of sandstone were chiselled and shaped by Ptolomy's masons.
I saw the giant, greenish granite statues that were lifted from the sea bed in the mid-1990s. They were part of the decoration of the lighthouse - statues of kings that every sailor would have seen as his ship passed through the harbour entrance.
When the ships docked in ancient times, they would have been visited by officials from the Great Library of Alexandria who went aboard every vessel searching for books.
It was not a matter of censorship, as it might be today. They were looking for books that they did not have. If any were found they were confiscated and given back later, but only after the scribes had made a copy for the Great Library.
But now, two millennia on, books are once again arriving by sea for the new library of Alexandria, which I could see taking shape on the corniche - a wide busy road on the sea front that is reminiscent of cities on the French and Italian Riverias.
The new library at the eastern end is a stunning building. Its main feature is a huge disc-like roof, 120 metres across and set at an angle so that from the breakwater where I was standing it glinted in the sun and in the distance looked like a giant communications dish.
It is really a building set on its side. Inside, all the reading rooms are arranged on terraces which makes it possible for almost every reader to work under natural light.
Another innovation is for the delivery of books. That will be computer controlled, and having ordered a book using a keyboard, the reader will simply watch it delivered automatically on a conveyor system right to his desk.
One day the library might qualify for the second division of architectural wonders. There are many who would like to find the original one first, but despite many excavations no sign of its ruins or books have turned up.
Hidden city
Ancient Alexandria has been almost wiped off the face of Egypt. When Napoleon came through in 1798 there were only two standing monuments: Pompey's pillar - a marble column standing 22 metres high and with a flat topped capital so wide that 18th Century visitors used to be hauled up to picnic on the top. The other standing monument was an obelisk, which is now in New York.
And not to be outdone, the British in the 19th Century crated up another obelisk that had lain half-buried near the shore of the harbour for centuries and named it Cleopatra's needle. They made a special barge and towed it all the way to the north bank of the River Thames in central London, where it still stands.
By the end of the 18th Century, Alexander the Great's city had simply fallen over and had been buried by time. But much of it survives under the ground.
When people began to build again on the same site in the 19th Century, a new cosmopolitan city rose on the ruins and sealed them.
Basements and foundations in those days did not disturb the archaeology, while the rest of the ancient city lay just offshore on the bed of the eastern harbour. Archaeologists say the seabed is littered with bits of ancient buildings and statues.
And divers have described swimming up to the granite face of a sphinx that had been crouching in the sand for more than 1,500 years since a catastrophic earthquake changed the contours of the city.
The fact is that one of the least known but richest, biggest and most important cities of the ancient world, is simply waiting to be re-discovered. Re-development should be giving archaeologists windows through which to record unknown details of the Greek and Roman townscapes.
Bulldozed
That is the theory, but in practice once a site is cleared developers move in mechanical diggers that overnight can easily scoop up 10 metres of ancient remains and dump them into skips.
At one building site I found archaeologists locked out even though they held a permit to excavate. The police were called but still the developer stood his ground - the police seemed to have a different agenda - and weeks went by before any archaeology could be started.
Sometimes archaeologists do not hear about the development until the building is under way and a new deep basement has cut through to 4th Century BC streets and houses.
There is so much that could be found - important buildings associated with Anthony and Cleopatra; temples that were described in ancient texts; the gymnasium; the forum; Greek and Roman theatres.
The Great Library of Alexandria would perhaps be the biggest prize. Although it was burnt down in 48 BC it is possible that the charred remains of papyrus books could have survived and after careful conservation could still be read.
As things stand at the moment though, the only person likely to glimpse any fragment, is the driver of a bulldozer.