For the next four years, the United Nations' nerve center, including Secretary-General Ban Ki-moon's office, will be situated in a squat, three-story, corrugated steel building on the U.N.'s north lawn that looks like a cross between a suburban big-box store and a high-security lockup facility.

Bantánamo, a nickname embraced by U.N. staffers, has taken much of the grandeur out of diplomacy at the United Nations. It's a serious comedown for U.N. civil servants and delegates who have been grinding away in the cause of peace in one of New York City's architectural landmarks, the glass and marble U.N. headquarters tower and the U.N. General Assembly hall -- now undergoing a $1.87 billion renovation.

"The morale among the people in the secretary general's office has never been lower," a U.N. official who works in the new building told Turtle Bay. "Everybody is profoundly depressed and demoralized because they are put into windowless, airless cubicles that are completely inhumane."

Some diplomats say the scaled-down, no-frills quarters send just the right message for an organization that has been struggling to shake off a reputation as wasteful. "It's stern and pragmatic but it's by no means ostentatious," said Heraldo Muñoz, Chile's U.N. ambassador, adding that governments, principally the United States, have unfairly criticized the organization in the past and starved it of cash. "Being in this temporary shelter reflects the state of the U.N. I feel we should be able to put it up with it for a few years."

The original U.N. headquarters compound was built in the early 1950s by a committee of internationally renowned architects, including the Swiss-French modernist Le Corbusier and Brazilian Oscar Niemeyer, who intended it to serve as a temple to international peacemaking, elevating the role of U.N. civil servants and delegates to a kind of diplomatic priesthood.

"Every time I come into that building I feel a sense of awe," said Stephen Schlesinger, author of The Act of Creation, which chronicles the founding of the United Nations. "It's now been reduced to a pile of shipping crates. This will diminish the United Nations."

There is little debate about the need for a full-fledged renovation of the U.N. headquarters compound, which has been showing its age. The elegant corridors linking the Security Council to the General Assembly chamber are riddled with leaks that let in rainwater. The heating and air conditioning systems are wildly inefficient, requiring a sweater to ward off the cold at the height of summer. The walls are filled with asbestos. Last year, New York Mayor Michael Bloomberg's sister, Marjorie Tiven, who heads the city's liaison officer with the U.N., threatened to shut down public tours of the U.N. because of rampant violations of local fire safety codes.

The new headquarters' airy industrial interior, with exposed air conditioning ducts on the ceiling and poured concrete floors, bears more of a resemblance to Wal-Mart or Ikea -- two other popular nicknames for the temporary space -- than to the U.N.'s original buildings.

The new building sits atop what was a large U.N. garden filled with statues from around the world. The crew was unable to move the largest statue, a 40-ton depiction of St. George slaying the dragon of nuclear war, and built around it. The statue -- built by the Soviet sculptor Zurab Tsereteli and entitled Good Defeats Evil -- is held in place by a massive concrete base and was constructed out of scrapped sections of U.S. Pershing and Soviet SS-20 nuclear missiles.

Niemeyer, now 102 years old and the only surviving U.N. architect, was appalled by the construction of the new building on the U.N.'s north lawn, and has advised the United Nations to take it down as soon as the renovation is complete. The U.N. says the new building has been constructed with Niemeyer's request in mind.

"It wasn't designed to be permanent or to be elegant or to be exotic," said Michael Adlerstein, a New York architect who built Bantánamo for $140 million and was appointed by Ban in 2007 to oversee the U.N. headquarters renovation. "It was designed to be functional."

At a ribbon-cutting ceremony last month, Ban celebrated the building's lack of pretension, noting that "there are no escalators. The windows are limited. We have simple concrete floors. No carpets."

Ban later acknowledged that there were, actually, some carpets, and some wood paneling, in his personal office -- "minimum decorations for the courtesy of visiting dignitaries and V.I.P.'s," he said.

Not everyone has it so good. The General Assembly president, Libya's Ali Abdussalam Treki, who also needs to meet with world leaders, was annoyed to discover he and his staff were to be crammed into a small set of offices that could only be reached by way of a dark concrete corridor.

Werner Schmidt, the spokesman for Adlerstein, declined to discuss Treki's concerns. But he acknowledged: "We are making some adjustments to the offices of the president of the General Assembly in accordance with his wishes." It is not unusual, he added, for "a high-level occupant" in any new building to find that "certain things can be improved."

Mid-level U.N. officials have groused at having to give up window offices with views of the East River and midtown Manhattan for the sunless cubicles. They are particularly bitter that the Group of 77, a loose but powerful alliance of more than 130 developing countries, has been given a fairly large space in the new building. In contrast, the U.N. General Assembly affairs office, which is responsible for organizing meetings in the building, has been moved to a space two blocks away from the U.N. compound, a 42nd street office above a luggage store. "It was blackmail," said one U.N. official, noting that the G-77 has used its influence on the U.N.'s main budgetary committee to exact a spacious set of offices.

The group's chairman, Sudanese ambassador Abdalmahmood Abdalhaleem Mohamad, said he "fought hard" to make a case for office space in the building. But he insisted there was no undue pressure. "We are an important actor in the U.N."

Muñoz cited a more practical problem with the new digs. "There is a lot of confusion," Muñoz said. "I found myself in the corridors of the new building meeting with other ambassadors and members of the U.N. secretariat. They know they have to go meet someone and don't know where the heck they are located."