A New York developer who once proposed building a high-rise hotel at Spring Point just bought the largest vacant office building in South Portland.

John Cacoulidis paid just under $10 million for an office building at 300 Southborough that is 116,515 square feet, according to Thomas Moulton, partner with the Dunham Group, which brokered the sale.

Moutlon described the transaction as a cash deal. Cacoulidis, who lives in Westbury, N.Y., could not be reached for comment.

Moulton, who represented Cacoulidis, said the seller was a Middle Eastern royal family that had owned the South Portland office building for six years.

The seller is listed on South Portland tax records as Scarborough Holdings LLC, and was represented by brokers from Boston.

Moulton declined to identify the royal family that sold the property to Cacoulidis but said negotiations took about a year to complete.

The Unum Corp. had most recently leased the building from the Middle Eastern owner but moved out 18 months ago.

Unum had been the building owner prior to selling the property in 2003 and staying on as a tenant.

The South Portland tax assessor valued the property at $15.9 million. The sales price originally was advertised at $15 million, but the difficult economy helped Cacoulidis negotiate a favorable deal.

Moulton said buyers with cash can find "really good deals" in the current commercial real estate market, especially with larger buildings that command top dollar.

The tight credit market has made it challenging for investors to raise the money to buy large commercial properties.

"Banks are really conservative in underwriting and requiring substantial amounts of money down," Moulton said about commercial lending.

Moulton said he does not expect Cacoulidis to have trouble filling the office space. A national insurance company already plans to move into a portion of the building, after it is renovated. Three other business tenants also are considering the site.

Cacoulidis will spend several million dollars to fully renovate the building and make it more energy efficient, including converting the electric heat to natural gas. Moulton said the goal is to meet LEED certification requirements, the industry standard for energy efficiency.

Moulton described Cacoulidis as a developer with a strong track record. He said Cacoulidis was the general contractor for the New York Yankees Stadium, when it was rebuilt in the 1970s, and a big government contractor specializing in airports and military bases.

He said Cacoulidis is currently building the world headquarters for Arizona Iced Tea at a site in Long Island, N.Y.

In Maine, Cacoulidis also has made a name for himself.

In 2001, he proposed building twin 41-story hotel towers and a convention center on 22 acres of South Portland's waterfront that he owns.

The complex would have been the tallest hotel in Maine. But Cacoulidis withdrew plans after twice failing to win local permits and encountering public opposition.

Moulton said Cacoulidis has not tried to propose any other ideas for the land in part because of traffic problems a major development would cause at the tiny point, which is near the campus of Southern Maine Community College.

Cacoulidis also owns commercial property in greater Portland. He has an office building at 2 Monument Square and is preparing to close on the purchase of the Portland Press Herald newspaper building.

The developer has a purchase-and-sales agreement to acquire the newspaper building at 390 Congress St., as well as two other nearby properties owned by Maine Today Media Inc. Moulton described the purchase as imminent.

The acquisition will include the newspaper's primary office building, its former printing press building across the street and part of a nearby parking garage.

"John Cacoulidis loves Maine and likes the people of Maine and sees a lot of potential here," Moulton said.

Although Cacoulidis lives in Westbury, N.Y., he and his wife, Phyllis, spend weekends on Hope Island, which they bought in 1993. They share a 20-room estate that includes horse stables and a helicopter pad.

Cacoulidis unsuccessfully tried to have Hope Island secede from the town of Cumberland eight years ago, because he objected to his property tax bill, but the Legislature refused to allow it.