OSWIECIM, Poland — By the side of the main railroad spur at Auschwitz, 14 Polish construction workers repair the death camp's barbed-wire fences. Concrete fence posts, cast by prisoners 60 years ago, are crumbling. For six years, an international preservation committee debated whether and how to restore them.

The fences ringing Auschwitz frame a dilemma: How best to memorialize one of history's darkest crimes? Refurbishing the place protects the Nazis' handiwork. But letting Auschwitz decay further could erase important evidence of the mass extermination.

The most wrenching decisions about renovating the death camp are still to be made. Should two tons of hair, shorn from dead prisoners and now turning to dust in its display case, be left on view or buried? Should the thousands of leather shoes taken from inmates be oiled to lengthen their life, or left covered with the mud in which they were found? Should the ruins of four gas chambers and crematoria remain exposed to the elements or be encased, like fragile art, to stem further deterioration?

A group of historians, religious leaders and survivors, grappling with the issues since 1989, is testing an uneasy compromise. They want to maintain the camp just as visitors find it today, a ruin that honors the more than 1 million people murdered here, 90 percent of them Jews.

The group is about to begin a new round of debate on some of the hardest questions, including what to do with the crematoria. Some historians argue that re-creating parts of the camp would show how genocide was carried out. Some preservationists counter that letting the site decay naturally would increase its emotional power. Survivors pursue a middle ground, saying whatever decision is made, the camp should be maintained indefinitely to bear witness when they no longer can.

"We hope to preserve it for after the survivors are gone," says Kalman Sultanik, an 84-year-old Holocaust survivor who heads one preservation committee, formed and funded by several European governments and the private foundation of cosmetics heir Ronald Lauder.

Auschwitz wasn't built to last. Constructed on swampy ground screened by forests, the camp housed its prisoners mostly in old horse stables and wooden shacks built from materials looted from nearby villages. The Nazis planned to complete their murderous work expeditiously, historians figure, and then destroy the evidence.

The first part of Auschwitz was built in 1940 to house political prisoners and other deportees and is marked by its iron gate with the cynical phrase "Arbeit Macht Frei" — "Work Brings Freedom." The vast bulk of the murders were conducted at the second, much larger camp, 1.5 miles away, at Birkenau, known also as Auschwitz II. That 430-acre site was a vast killing factory, with nearly 300 barracks and four large buildings with gas chambers and crematoria. The remains of red brick chimneys that once heated prisoner barracks stretch to the horizon.

Before Russian troops liberated Auschwitz in 1945, Nazi SS troops dynamited the gas chambers and crematoria in an effort to obliterate evidence of their crimes. After liberation, local residents looted the camp in search of building materials and prisoner valuables.

In 1947, Poland decreed that Auschwitz be preserved as a museum, and as testimony to Nazi atrocities. But the communist government, lacking a plan and significant funding, made only haphazard efforts at preservation.

The entrance was moved to make room for a parking lot. The sauna, where prisoners were stripped of their belongings, showered and tattooed with identification numbers, was outfitted with a handsome new roof that makes the building look like a modern administrative center, marring its authenticity. In a corner of Birkenau, brick barracks were renovated with modern roof tiles and top-grade masonry. Now conservators let the grass grow high there to discourage visitors.

Large swaths of the camp complex vanished. Wildlife chewed wooden buildings, moss weakened mortar, and wind and rain battered what remained. Conservators managed to save fewer than one-quarter of the concentration camp's wooden buildings.

The situation is even worse at many other concentration camps, which don't get as much attention or funding as Auschwitz. Treblinka, Belzec and Sobibor in Poland, Dachau and Bergen Belsen in Germany use memorial markers or recreated displays because original buildings were destroyed by the Nazis or deteriorated over the years, leaving Auschwitz the most complete example.

In 1989, Mr. Lauder, whose New York-based foundation supports Jewish educational projects and sites in Eastern Europe, visited the Auschwitz complex, which attracts about half a million visitors each year. Shocked at its condition, he raised funds and set up a committee to draft a conservation plan. Altogether $12.5 million has been spent since 1992. Germany has supplied about $8 million to repair museum buildings, windows, gates and guard towers, including the $2 million tab for the fence-post repairs. France, Greece, Russia and Switzerland are paying for a $3 million conservation laboratory, set to open next year.

The preservation committee discussed suggestions from a wide range of experts. Jean-Claude Pressac, a French historian whose books debunked revisionists' denials of the mass extermination, favored rebuilding a crematorium as a "slap in the face" to all doubters. But the committee was influenced more heavily by James Young, a University of Massachusetts professor of Judaic studies, and Tony Frantz, chief conservator of objects at New York's Metropolitan Museum of Art, who both favored less intervention. "Part of (Auschwitz's) emotional impact has to do with it being experienced as an archaeological ruin," Mr. Frantz says. "It's not an art museum. It's a cemetery."

In its initial report, in 1990, the committee favored a middle approach, not altering the site, but not allowing further decay. After urgent repairs were made, some preservation committee members and the Auschwitz museum staff turned to the fence posts in 1995. Over the following six years, the staff examined the best technologies for repairing concrete. At a 1999 conference attended by museum staff, some committee members and Polish government designees, the group worked out a new compromise. The fences that were still needed for security would be rebuilt to look as they did in the 1940s, but the rest would be preserved as they were found.

Some issues remain so emotionally wrenching — and so technically daunting — that they have been put off limits so far. Until the early 1970s, museum workers used to dust the two tons of prisoners' hair on display in a former Auschwitz barracks by lowering the hair onto a net and shaking it. Now, the hair is so fragile it can't be moved. Instead, it has deteriorated, its color fading into wiry black and gray nests.

Mr. Young says what's left must be kept as long as possible as "evidence of the sheer numbers" killed. But Jerzy Wroblewski, director of the Auschwitz museum, would prefer to bury the hair, out of respect for the families of the dead, and because he isn't sure what else could be done. "If it were one curl, we could create a special (preservation) chamber," he says. "But it's impossible to do with the quantity we have."

Similarly, the conservators are stymied by the thousands of mud-caked shoes once worn by prisoners. For years, they used a large tumbling machine to apply a layer of oil to the shoes and keep them from cracking. But the last time that was tried the stitching in many of them fell apart. The camp then asked German students to do the work by hand, but stopped the program when the work seemed futile.

Now, a different problem looms: bugs that feast on the leather. Another concentration camp in Poland, Majdanek, is experimenting with using radiation to kill the insects. On a recent visit to Auschwitz, the shoes sat in a glass case, a moth hovering over them.

Work continues on the fences, at the side of the railroad spur in Auschwitz II. Sixty years ago at the spot, SS troops would sort newly arrived prisoners into two groups — some headed for the sauna to be readied for work, but most to be gassed. Now, rows of decaying posts, each reinforced with four steel rods which frequently protrude from the concrete, line the rusted tracks and the rough gravel road beyond. When water seeps into the concrete posts, the steel rods corrode and expand, putting pressure on the concrete and causing the posts eventually to burst open.

The work is taxing in ways the crew hadn't imagined. They labor in silence between the prisoners' barracks and the crematoria, with only the sound of the wind competing with the tapping of their chisels. "Whichever direction I look, I feel a burden," says Stanislaw Papiez, the 51-year-old construction chief. "There is no way you can look and find peace."

The 3,600 arching fence posts, which were once joined by electrified barbed wire, figure prominently in prisoner memoirs as symbols of captivity and hopelessness. Some desperate inmates threw themselves against the wire to commit suicide. Today, aging survivors sometimes ask Auschwitz for rusted bits of barbed wire, which are cut from the only surviving coil.

The fences still offer glimpses of the prisoners' lives. Segments are marked by production dates and by prisoners' identification numbers scratched into the concrete. Spoons, forks and even a tiny metal lamb, probably a toy, have been unearthed near the base of some poles. "Even at the bottom of a post you find pain and suffering," says Witold Smrek, Auschwitz's chief preservation engineer, whose grandfather was deported to Auschwitz and perished in another death camp.

The fences near the railroad spur are still used for security, though the barbed wire has been replaced and the electricity turned off. They require extensive work to restore them to their original look and strength, down to the cheap-grade concrete, studded with pebbles.

It is a somber workplace. Konior Sp.j., a construction firm from nearby Katowice, manages the work and forbids the crew to play radios or talk with tourists. Out of respect for the setting, there is little banter, and the workers wear uniforms of white canvas coveralls.

Along with many of the crew, Grzegorz Fajferek, a tall blond worker, comes from Oswiecim, the town outside Auschwitz's gates. (The Nazis Germanized Oswiecim's name to Auschwitz.) His grandmother once worked nearby, as a domestic servant in a Nazi officer's house.

Mr. Fajferek has chiseled one post, carefully loosening slabs of the original concrete that would have later fallen off and laying them to the side. He has sprayed the concrete with a chemical that prevents further crumbling and coated the steel rods, sandblasted free of rust, with anticorrosion paint.

Now, he is ready to reassemble the pole, like a jigsaw puzzle. He mixes mortar with the right size of pebbles to match the original, and scores a concrete slab with an electric saw so it will adhere better to the post. After reattaching each concrete part, he will fasten it with a clamp to dry for three days. Refurbishing a fence post can take a month. "The most difficult thing is to get the look right," says Mr. Fajferek.

Fence posts in the interior of the camp are sandblasted free of rust and coated with anticorrosion paint, but then get another treatment that mimics the original rusted look. They still look like ruins, but ones that should be able to withstand another 50 years of weather erosion.

During breaks, the crew sometimes tries to imagine how starving prisoners managed to build the fence they're repairing, whose posts are spaced and aligned precisely. It's summer now. How could the prisoners have worked through frigid Polish winters protected only by a prison uniform? Each of the 12-foot posts weighs about 650 pounds and must be buried a yard deep into the soil. It takes four brawny workers now to lift one concrete post. How many prisoners did the lifting? "It must have been eight," says Mr. Papiez, the construction boss. Then he reconsiders. "The prisoners were underfed, weak. It must have been more than eight."

He thinks of his own relatives who, though Catholic, suffered too at the hands of the Nazis, as did many Polish Catholics. "My grandparents died here," he says, wiping away tears. They were deported from nearby villages and never heard from again.

A few hundred yards away from the fence post restoration are the remains of two crematoria. In the 1960s, the Polish government erected steel braces to keep the massive concrete roof from collapsing entirely onto the remains of the gas chambers and ovens that the Nazis had dynamited. But a wall lining the entrance to the gas chamber collapsed within the last decade. Big chunks of a crematorium roof dangle a foot above the ground, held by reinforcing steel rods which will soon snap.

Museum staff spray the ruins with herbicides to prevent lichens from weakening the concrete. They drain the site after heavy rain. But nothing more is done to keep the ruins from deteriorating, because of the lack of consensus over how to preserve them.

Next month, a group of Polish government preservation engineers will meet at Auschwitz to assess the crematoria. The following June, a committee of preservationists, survivors and religious leaders will gather at the death camp in hopes of finally agreeing to a plan. Among the possibilities: rebuilding one of the four Birkenau crematoria to its 1940s state while leaving the rest as they are, constructing a walkway or an entire building around the site, building a chimney-shaped memorial with photos of those murdered, or simply letting the place decay further.

Standing on the edge of the crematorium, Mr. Smrek, the camp's 47-year-old conservation chief, is overwhelmed by the scale of any reconstruction. The concrete slabs weigh tons. How could they be lifted, coated with chemicals and mortared together, without breaking further? Should the refurbished parts be slid back into place upon piles of bricks and the broken remains of crematorium ovens? The thought of construction cranes wrecking the stillness and solemnity of Auschwitz is unsettling enough. Erecting a building to protect the site, however well intentioned, would permanently alter the landscape. "It doesn't fit," he says. He isn't sure what would.