Billed as the tallest office building between D.C. and Dallas, the Georgia-Pacific Center soars 51 stories over Peach Tree Street, dominating Atlanta's skyline with its polished red granite facade.

It cost co-owners Georgia-Pacific Corp. and Metropolitan Life Insurance Co. $150 million to build. Its rental rates are higher than those charged by any other building in the city.

And eight months after it opened, the Georgia-Pacific Center remained nearly half empty, proof that firms with billions in annual sales are not immune from bad real estate markets.

"We call it the premier office building of the Southeast," said Tom Ryan, a spokesman for the forest products giant. "We're proud of it."

He predicted that the property will be fully leased by the end of this year. But so far, Georgia-Pacific has the place pretty much to itself.

The firm, which moved its corporate headquarters from Portland, Ore., to Atlanta last year, occupied floors 2 through 22 and the building's penthouse--about 51 percent of the center's 1.3 million square feet of usable space.

The floors intended for lease to other firms, 23 through 50, sit unfinished and empty, expanses of concrete and exposed wiring waiting for tenants.

A promotional campaign that cost between $250,000 and $500,000, according to leasing agent Michael Elting, so far has netted the building just two major tenants. Arthur Andersen & Co., Georgia-Pacific's accountant, will begin occupying four floors in September, while Bankers Trust Co. will take most of another by the end of the year.

For now, a four-room travel agency is the only occupant of the tenant floors.

Georgia-Pacific, which had sales of $5 billion last year, decided in 1978 to move its headquarters from the West Coast to Atlanta. "We wanted to be nearer our operations," said Ryan. "Seventy-five percent of our sales and manufacturing are east of the Rockies."

At the time, Atlanta's real estate market was enjoying its first good year after the mid-'70s office space glut that hit the area harder than the nation as a whole. The vacancy rate downtown had fallen from 28 percent in 1976 to the low teens, according to Harry Saxton of Redi/Databank, a research firm here, and absorption of office space was high.

"It was very bullish, and I'm sure they thought they would catch the bottom of the wave, but then '81 threw them a curve," Saxton said.

High interest rates and the recession cut the number of firms looking for space, and a surge in suburban construction lured many potential clients from downtown.

"Atlanta is in much better shape than some place like Houston," said William Beak, who heads up the regional office of Arthur Rubloff & Co. "But the market is definitely soft, and that's hurting Georgia-Pacific."

Also hurting the office center are the rental rates, Beak said. They range from $22 to $27 a square foot--$10 a square foot more than rates charged for existing first-class space downtown.

Both Beak and Saxton predict that the center will fill up eventually, though not until 1984 at the earliest, and both say it will play an important role in preventing the decay of Atlanta's central business district.

"Considering the kind of year 1982 was, they haven't done badly, although normally two years to fill up would not be acceptable," Saxton said.

"I'm glad it wasn't my money going to pay off the loans, but then, with these people, the pockets were real, real deep. . . . Otherwise, it would have created a new line of work for the developer," he said.

Georgia-Pacific officials would not disclose their losses on the building, if any, its current revenue, and the carrying costs on the center's debt.

Part of a $33 million write-off that the firm took in the fourth quarter of 1982, however, related to the center, according to Rich Good, Georgia-Pacific's manager of investor relations.

In the long term, the company believes that the center will prove a good investment and justify a 1978 decision to build downtown and beyond the company's immediate needs for space.

"I don't know anybody who can predict the real estate market, do you?" Ryan asked. "In the long term, we're looking at this building as a good investment.

"We're a more-than-$5-billion-a-year company, and we want to look that way."