James D. Klingbeil, the man who became one of Arlington's biggest landlords last week, is a multimillionaire real estate developer from Ohio who owns a string of properties from coast to coast.

Klingbeil plunged into the Arlington real estate market by spending $48 million to buy Paramount Communities, a 200-acre package that includes four apartment complexes, two small neighborhood shopping centers and a large tract of vacant land. It was one of the biggest real estate transactions in Arlington in recent years.

Klingbeil, interviewed during a visit to Washington this week, said he does not plan to convert any of the complexes to condominiums. He said a major three-year rehabiliation of Buckingham, the largest and oldest of the four, would begin in the next two months. Klingbeil said he expected that tenants would not be displaced.

The high-rise Hyde Park and Chatham apartments will continue to operate unchanged, Klingbeil said. "I don't quite know what to do with Claremont," he admitted. Like Buckingham, Claremont is a garden apartment project that houses a large number of elderly people and families on fixed incomes.

"We basically bought it as a long-term real estate investment," said Klingbeil. His partner in the deal is Eugene Rosenfeld, a Los Angeles homebuilder and long-time business associate.

Klingbeil, 42, scarcely looks the part of a little-known multimillionaire developer who breezes into town, beats out several New York buyers by plunking down millions of dollars for a property that's been on the market for over a year and assiduously shuns publicity, but that's what he is.

"I'm a long-term real estate holder," said Klingbeil, who sat hunched forward athletically, his elbows resting on his knees, his hands clasped together. Dressed in a brown, pin-striped suit and shiny orange tie, he wore neither jewelry nor wristwatch.

"While condominium conversion is a possibility, it seems that the property is good as a long-term asset," said Klingbeil who has built apartments and townhouses in Springfield, Reston and Columbia. "We don't do a helluva lot of looking at Arlington. To me the location is incredible. I thought ($48 million) was cheap."

Klingbeil's rehabilitation plans for Buckingham, which was built in 1937, include air-conditioning the apartments, putting in new kitchens and laundry rooms and extensively landscaping the grounds. Klingbeil said he expects the improvements will cost tenants a maximum of $50 per month in rent increases. Rents currently range from $198 for a one-bedroom apartment to $310 for a three-bedroom unit.

"Arlington has one choice," said Klingbeil who apparently views Buckingham as a microcosm of Arlington. "Does it want to be a declining lower-middle class community or does it want to be an upper-middle class community? It's got two things going for it: location and convenience. Its long-term future has to be to continue to upgrade its housing.

"Buckingham is built like a fort. There are copper gutters, slate roofs, parquet or solid oak floors. But I think the kitchens are the pits and the grounds are lousy. Have you been to the laundry rooms there? They're horrible: two dryers blowing away, not enclosed, and the washers just empty into this big barrel in the middle of the room. I can't believe anybody goes to town there."

Among his chief concerns, Klingbeil said, is proving housing for a variety of tenants and improving the deteriorating "quality of life" at Buckingham.

"Are you single?," Klingbeil asked suddenly. "Let me ask you a marketing question. What do you think of a setting aside a section of Buckingham for single girls - not banning men or anything - but putting a heavy emphasis on security? I think if you analyze a lot of tenancies you'd find a lot of single women living there on the lower end of the wage scale.

"I don't want to throw out the Vietnamese or the elderly and substitute them with girls, but we try to cater to tenants' needs. "I'm just thinking out loud, buy maybe we could take 500 units and specialize in 'over 50' tenants. I'm trying to find out what it is these people want."

He said several members of his staff would be poring over rental records in the next few weeks trying to determine the types of tenants who live at Buckingham.

Klingbeil, his wife and four children are spending this year living in a building he owns in San Francisco. "I commute to Columbus once a week," he said, noting wistfully that he sold his airplane and now travels by commercial jet.

A native of a small town in Ohio and a graduate of Ohio State University, Klingbeil built one of his first projects when he was a first-year medical student at Stanford University in the late 1950s. "I borrowed a lot of money," he recalled, "and then took a year's leave of absence to finish it and never went back."