Behind the walls of Building No. 10, in a row of tan metal warehouses, lies the B-29 bomber that foreshadowed the end of World War II and ushered in the nuclear age.

Stripped of its wings, wheels and engines, the Enola Gay seems far too small to occupy such a large space in history. But this is the plane that enabled 12 Americans to attack 350,000 Japanese and to kill more than a third of them.Now, two generations later, the Enola Gay is in the hands of the Smithsonian Institution and is being restored at the museum's Paul E. Garber Facility in suburban Maryland. A handful of craftsmen are busy separating every nut from every bolt, and cleaning away 43 years of dirt and corrosion.

In places, workers have buffed and polished the dull aluminum shell of the fuselage, with its distinctive greenhouse-like cockpit. There, under the gray film of decades, is the gleaming silver warplane that appeared over Hiroshima on Aug. 6, 1945.

Robert C. Mikesh, the Smithsonian's senior curator for aeronautics, says the restored Superfortress is likely to go on permanent display in 1994.

The display is likely to revive the debate on whether the nuclear bombings were necessary. Some believe they ended the war early and saved lives, Japanese as well as American. Others believe that the luckless inhabitants of Hiroshima and Nagasaki were vengefully singled out to pay for the sneak attack on Pecities against American prisoners of war.

The Smithsonian intends to display the plane without choosing sides; without seeming to shame the Japanese ("There is absolutely no point in any hurrah," Mikesh said) and without apologizing for the attack, either.

"What is it we are trying to portray? It is a historical event, a historical object, and our only purpose is to preserve the history and the technology," Mikesh said. "How people want to interpret that is for their choosing."

The Japanese government has said it will not comment until the Enola Gay is unveiled. Makoto Hinei, cultural attache at the Japanese embassy, said it was "a delicate question" to anticipate how the exhibit might affect Japanese sensibilities.

"It really depends on the nature of the display," he said.

Exploring the dark corners of these warehouses in Maryland is akin to rummaging through the Smithsonian's attic. About 329 historically important aircraft are stored here. Some are set up under primitive display conditions. Many others are simply stored in a jumble, pelted by rainwater from leaky roofs.

This is the first stop whenever an interesting plane is discovered in a barn somewhere in Europe or in a South Pacific jungle. Here it awaits the attention of a handful of expert toolmakers and metalsmiths, like the ones at work on the Enola Gay.

Built in the American heartland, in Omaha, Neb., the Enola Gay is the single most important artifact stored here. It is a plane that confronted its creators with a question they had never foreseen: whether the means of ending a war could ever be more terrible than the war itself.

Workers will repaint the chipped, black letters bearing the first and middle names of Enola Gay Tibbets, the mother of the Hiroshima pilot, Col. Paul W. Tibbets Jr. His own name will be removed from under the pilot's window. Photos confirm that Tibbets, now living in Ohio, had his name painted there some time after the bombing. (Capt. Robert A. Lewis had been scheduled to fly the mission, but at the last minute he was bumped into the co-pilot's seat by Tibbets, the squadron commander.)

Since there is no room to display the Enola Gay at the National Air and Space Museum in Washington (the plane has a wingspan of 141 feet), the Smithsonian intends to build a complex of new buildings at Dulles International Airport, or at Baltimore-Washington International.

The focus will not be on the Enola Gay. The space shuttle Enterprise and the prototype Boeing 707 will go on display at the same time.

("Bock's Car," the B-29 that dropped a plutonium bomb on Nagasaki three days after the raid on Hiroshima, is on exhibit at the U.S. Air Force Museum at Wright-Patterson Air Force Base near Dayton, Ohio.)

Tibbets set out to bomb Hiroshima from an airfield on Tinian, in the Marianas islands, about 1,500 miles from Japan. Five and a half hours after takeoff, the bombardier sitting in the glass nose of the Enola Gay released a 9,000-pound bomb called "Little Boy." Tibbets banked the plane sharply, having been warned to expect a blinding burst of light.

Though the bomb would not explode for another 43 seconds, the crew of the Enola Gay had just killed more people than nearly 300 Superfortresses did in a two-hour firebomb raid over Tokyo.

Little Boy exploded about one-third of a mile above the city, instantly killing 78,000 people. It erased the landscape in a blast hot enough to vaporize steel. Another 42,000 people had been dealt fatal injuries, and many others had been exposed to harmful doses of radiation.

The bomb did not discriminate. It leveled munitions factories, but also schools and hospitals It wiped out the Japanese 2nd Army, 23 American prisoners of war and thousands of Japanese mothers and children.

Those it did not kill became known as the "Hibakusha," the world's only survivors of nuclear war.

By the time of the second atomic bombing, at Nagasaki, Emperor Hirohito had grasped the meaning of the new weapon. In announcing the surrender on national radio, he said civilization itself was threatened by this "new and most cruel bomb."

As Mat Romankiw, a Smithsonian guide, recently led a group of tourists through Building 10, an elderly woman spotted the unique name from 50 feet away. She held a hand to her mouth and said softly, to herself, "Oh my. The Enola Gay."

As a young man, Romankiw served in the Army infantry in Europe. In 1945 he was sent home to train for the planned invasion of Japan. Standing before the Enola Gay, he said to his tour group, "I'm convinced that it saved my life somewhere along the line, so I have no hard feelings about the Enola Gay."

Privately, Romankiw said, "I think it was an awful thing. I just cannot imagine killing all those people. But it was an expedient thing that had to be done.

"I'm a realist," he said. "I didn't attack Japan; Japan attacked us. You cannot deny history."