Being awestruck will become much harder when the pyramids are surrounded by urban sprawl. They will be engulfed by greater Cairo by the turn of the century unless two supertankers are rapidly turned.
The first is urban population growth, which has seen Cairo's numbers double to around 13 million in two decades as people flow in from the irrigated lands all along the Nile and its delta and raise families.
The second supertanker is the Egyptian capital's own version of the M25, which has been under construction for many years. When complete it will come within two miles of the pyramids and cut them off from the open desert to the south. New housing and businesses are bound to follow.
Next week Unesco, the United Nations' culture and heritage arm, will ask the Egyptian government to find a way of sparing the pyramids from the sprawl. Yet Africa's largest city desperately needs room to grow. Even if population growth could simply be turned off like a tap, the people and families already in Cairo would still need more room. It is among the world's most densely packed cities, with millions living in small, airless hovels.
Today, the necropolis of six square miles, perched on a plateau, is still almost surrounded by desert. You can take a photograph that shows the pyramids of three fourth-dynasty pharaohs - Cheops, Chephren and Mycerinus - set in rolling sands. But a cemetery, a hotel and the Cairo suburb of Nazlat al-Samman press against the plateau's eastern and northern flanks. In the Fifties, this settlement was a tiny hamlet. Now its tightly packed roads and buildings cover archaeological remains associated with the Cheops pyramid, the largest of the three, and come within 200 yards of the Sphinx.
Fifteen years ago there were several miles of farmland and the odd villa between Cairo and the monuments. As you approached them down Sharia al Haram, a long, straight road, you watched them grow from little triangles on the horizon into age-pocked, man-made mountains. Now the houses and buildings of Giza on the city's eastern side no longer peter out and you are almost there before the pyramids pop up above blocks of flats.
The grandeur of the ruins is already diminished by the city's proximity. Visitors need tranquillity, time, information and plenty of space if they are fully to appreciate the pyramids and the achievement of their creators. If Cairo surrounds them entirely it will become hard to grasp how or why an early agricultural civilisation of a few hundred thousand people built such immense, time-proof structures with such precision. Egypt is gambling with one of its most important foreign currency earners.
It is not easy to be optimistic about the pyramids' chances of averting encirclement because the city's growth is disorganised and remorseless. Shacks and multi-storey buildings go up without an infrastructure of roads, water mains and sewers. Such is the demand for space that several million Cairenes live in two huge cemeteries, the Cities of the Dead.
The 66-mile Cairo ring road is one large piece of infrastructure which is going ahead, although fitfully. The city has metro and railway networks but buses and cars dominate and the hot air is fouled by fumes. Miles of dual-carriageway flyovers, swarming with a jostling, honking mass of vehicles, weave through the city's core. The ring road's purpose is to take suburban and through traffic away from the centre. More than half of it has been completed and the remainder is due to be finished in the next two years. A crossing for the road over the Nile is under way.
'It is a real threat,' says Dr Hassan Imam, director of Cairo University's engineering faculty. He points out that a new town is already being built in the desert a couple of miles west of the pyramids. 'The new road will attract many small settlements to the south.'
In his office on the other side of the city the man in charge of Egypt's heritage dismisses talk of encirclement. Professor Mohammed Nur El Din, chairman of the Supreme Antiquities Council, says the government will simply have to ensure that this time there will be no development along the new road. 'It happened and we weren't able to control it - we're trying to control what's new,' he says.
The Supreme Antiquities Council plans to make improvements on the pyramids' plateau itself. Within the next three years several million pounds are due to be spent installing new facilities for visitors and conserving the ruins. But besiegement by Cairo would spoil the effect.
The improvement programme began with a plan commissioned by the Supreme Antiquities Council and Unesco. It was drawn up by the Conservation Practice, a British consultancy, which has proposed . . . a ring road; although this one is tiny compared with the motorway around Cairo.
The tourist road will allow visitors' buses and taxis to circle the edge of the plateau instead of driving through the middle. The existing tarmac roads that nestle up to the pyramids will be removed. Three separate visitor centres will be spaced along the new road, housing gift shops, cafes and exhibits explaining the Sphinx, the pyramids and tombs and something of the civilisation and religion that created them.
Several presidents, including President Hosni Mubarak, have built themselves residences near the pyramids; these and some other modern buildings are to be demolished. As much as possible of the 20th century will be swept from the plateau. Visitors will have to walk a few hundred yards from their vehicles parked beside the new road in order to be among the stones. There may be battery-powered vehicles to carry the elderly or handicapped. The camel and horse rides that are pressed on every tourist will continue, perhaps with a little more control.
Further work on the plan has been done by Dr Imam's department at Cairo University and it is nearing completion. Professor Nur El Din says the building work will be put out for tender in the next few months.
Unesco holds dollars 3m in trust for the Egyptian government, which could cover much of the costs. (Part of this fund came from entrance receipts as Tutankhamun's treasures toured the world's museums.) There is also scope for raising the entrance charge for tourists - it costs about pounds 2.50 to enter the site with a car.
The plateau is one of Unesco's World Heritage Sites. As such, it should be surrounded by a buffer zone, legally protected from development. But the Giza pyramids gained this designation without the zone being guaranteed. It was a big but understandable mistake by Unesco, for the pyramids were crying out for a rapid nomination as a World Heritage Site.
The new tourist road will mark out a buffer zone of sorts - but it will be very small, only a mile across. When the Cairo ring road arrives and development presses in from every side the pyramids will be left in a desert park surrounded by city.
There are dozens of lesser pyramids a few miles to the south, some buried under sand, which may also be affected by ring-road sprawl. The Conservation Practice and Unesco fear for the remains of ancient Memphis, founded in 3100 BC, and the very first of the pyramids, King Zoser's at Saqqara, some 20 miles south of the city centre.
Next week Said Zulficar, a senior Unesco official who is Egyptian, will fly from Paris to Cairo to meet ministers and civil servants from Egypt's ministry of culture and the Supreme Antiquities Council. Once again he will protest about the Egyptian government's failure to secure the pyramids' surroundings. 'We were never told about the plans for a greater Cairo ring road,' he says. But he recognises that larger ministries dealing with the infrastructure and housing have more clout. 'Unfortunately culture is one of the weaker ones,' he says.
The outcome of this struggle between development and conservation depends on the level in government at which the arguments take place. Local politicians press the case for development, under pressure from businesses and people in need of homes. The best hope for the pyramids is for the dispute to go all the way to Egypt's prime minister or president, under the glare of international publicity.
The pyramids will endure for centuries more. But to leave them stranded in a park within a mega-city would be a cruel 20th-century joke to play on the ancients who defied time.