BAMIYAN, Afghanistan (CNN) -- At the foot of cliffs in central Afghanistan, about 5,000 fragments of what were once among the world's great artistic and religious treasures, the Buddhas of Bamiyan, sit in rudimentary shelters.

Their destruction by the Taliban in March 2001 was an act of cultural vandalism on a spectacular scale. The two tallest standing Buddhas in the world -- which had stood as silent sentinels over the snow-capped valley of Bamiyan for more than 1,500 years -- were reduced to mere rubble.

Wire mesh now covers the cliffs to prevent them from deteriorating further, while archaeologists and restoration experts have cataloged the fragments that remain of the giant statues.

The recovered pieces -- many the size of large boulders, others as tiny as pebbles -- are stored in the shelters while the archeological team decides whether to proceed with restoring the statues.

And that's just it: More than three years after UNESCO, the United Nations' main cultural agency, declared Bamiyan to be a World Heritage site, no one knows if the statues can ever be saved.

"No decision has yet been made about whether the Buddhas can be restored," said Abdul Abbasy, who heads Afghanistan's ministry responsible for the country's monuments and cultural heritage.

Carved out of sandstone cliffs, the larger male Buddha once towered 170 feet above the valley, as high as a 15-story building, while the smaller female Buddha stood around 10 stories tall.

The statues had survived the ravages of Mongolian conqueror and warrior Genghis Khan, centuries of wars and the natural wear and tear of the elements. But in 2001, despite protests from around the world, including from Muslim nations, the Taliban used explosives and tank fire to destroy Afghanistan's most famous tourist attraction.

The Taliban ordered their destruction as part of its campaign to destroy pre-Islamic artifacts considered an assault on Islam.

Today, some see the influence of al Qaeda behind the destruction of the Buddhas, which came in the months before the September 11, 2001, attacks on the United States. Al Qaeda had brought its extremist Wahabbist version of Islam to Afghanistan while the Taliban were in power, critics say.

The governor of Bamiyan, Dr. Habiba Sarabi, the only female governor in the country, told CNN, "It was al Qaeda or some other foreign power."

No apology from Taliban

A sense of the enormity of restoring the Bamiyan Buddhas can be gained by visiting Kabul Museum, in the Afghan capital, which once housed one of the world's greatest collections of Buddhist art.

In the weeks before the Taliban destroyed the giant Buddhas, they also entered the Kabul Museum wielding sledgehammers. They smashed 2,500 priceless artifacts stored there.

"It was a sad action," said museum director Omar Khan Masoudi, who has worked at the museum for almost three decades.

Asked if the Taliban had ever apologized for their actions, he smiled slightly and said, "No."

In 2003, with the support of the governments of France, Britain, Italy and Japan, work was begun not only restoring the destroyed artifacts, but also rebuilding the museum, which had been destroyed in Afghanistan's civil war during the mid-1990s.

Where once the roof was open to the sky, the museum is now almost completely rebuilt.

In the museum restoration room, technicians wearing white overalls working from old photos have been painstakingly restoring around 300 of the destroyed artifacts in the past five years. At that rate, it will take another four decades to restore the rest.

The slow progress at the Kabul Museum suggests that the restoration of the giant Buddhas will take many, many years -- if it is even possible.

Back at the cliffs overlooking Bamiyan, a gaping hole remains where the Buddhas once stood. Like so much in Afghanistan, a country destroyed by decades of war, restoring the country's cultural heritage is a task that will likely take decades.