ACROPOLIS CONTROVERSY

UNDER a cream-colored tarp that protects them from the hot Greek sun, four craftsmen hunch intently over a large block of partially sculpted marble, consulting calmly as they measure and pencil their next cut.

With the Parthenon towering just behind and the Greek capital shimmering quietly below, the peaceful scene fails to give the slightest hint of polemics.

But controversial it is.

The four men cutting a replacement drum for one of the Parthenon's damaged columns are part of a painstaking, long-term project to restore elements of Athens's Acropolis and to repair the damage caused by centuries of use, abuse, destruction, misguided reconstruction, weather, and most recently, atmospheric pollution.

In its 17-year existence, the Acropolis restoration effort has already been subjected to some of the broadest and most detailed scrutiny given to any project of its kind. It remains subject to periodic fits and starts as world-renowned archaeologists, historians, and architects pursue a long-running debate over whether such ruins should be rebuilt or left alone.

"There are ardent supporters of `didactive restoration,' who say, `Let's redo it all,' " says Petro Calligas, the archaeologist in charge of the Acropolis and director of the Acropolis museum.

"And on the other extreme are those who say, `Keep it exactly as we find it, and leave all the blocks on the ground,' " he adds. "We are working somewhere in the middle."

"We" is the committee of experts who have been working on the Acropolis restoration since the Greek government got serious in 1975 about halting and even reversing the destruction of one of the world's most cherished monuments.

And although this "working in the middle" has led to reassembled walls, cornices, and columns where restoration can be accomplished with a hefty majority of positively identified original materials, it also means that other features - like the Parthenon's long-gone roof - will never be rebuilt.

Controversy over the Acropolis, a stunning natural rock that has been occupied for more than 4,000 years and knew its height of glory 2,400 years ago, is nothing new. In 1875, a public uproar was set off when archaeologists decided to tear down a Frankish tower that had been on the Acropolis since the late 14th century.

"Since then," says Dr. Calligas, "the question has remained, `Do we return the Acropolis to the way Pericles built it, or do we preserve it as time and history have shaped it?' "

That question dominates today's controversies as well, the most recent of which concerns restoration of the Parthenon's pronaos, or antechamber, inside the building's east facade.

The Acropolis restoration team's senior architect, Manolis Korres, drew up four proposals for the six-columned antechamber's restoration. The boldest option, which called for full restoration with substantial use of new marble, was endorsed by experts from around the world when a periodic international conference on the Acropolis was held here recently.

But the Acropolis committee endorsed a "middle" proposal that calls for full restoration of only three columns, with the other three rising as high as "pieces found lying out on the ground" will allow, according to Calligas.

Another recent debate concerns preservation of sculptures remaining in the various temples.

The increasingly dense air pollution in Athens has accelerated the process by which airborne sulphur transforms surface marble into gypsum, a soft material. Rains then wash away the softened surface.

"Since we cannot stop the `gypsification' of the marble, we are faced with the terrible prospect of removing sculptures from the monuments," says Calligas. "But we decided it's either that or lose irreplaceable sculpture."

If nothing else, the recurring controversies have helped the Acropolis committee hone a basic set of rules or principles that will govern the restoration effort.

First, "We undertake restoration with as much original material as possible, and we only add new material when it must be used as minor fill to keep in position a greater amount of ancient stone," says Calligas. "If there is a destroyed wall for which only half the original material can be found, it will not be restored."

Second, the committee has adopted a "reversibility" rule, which dictates that any restoration undertaken must allow a dismantling if future generations decide that the restoration should be undone.

Third, modern construction materials should replace damaging materials used in the past.

For example, the iron clamps and bars widely used in restoration early in this century accelerated physical degradation, since iron expands as it decays. Much of the iron has now been replaced by titanium, a material used in shipbuilding.

Calligas estimates that "at least" another decade will be needed to complete the major restoration outlined by the Acropolis committee. By then a new Acropolis museum, down the rock's southern flank, should be open as well.

And while work on top of the rock proceeds, Calligas won't be surprised when new controversies bring the restoration debate back to the surface.

"When you're dealing with a monument that everybody in the world cares about," he says, "it's unavoidable."