The 51-unit loft building has a distinctive translucent green copper façade. But it, and a 203-unit apartment building to be completed this fall, also stand out as the grand finale in the 20-year development of this once controversial project.

The 21-building complex on the outskirts of Central Square contains 1.5 million square feet of first-class lab/office space, a 210-room hotel, two restaurants, a day-care center, parking for 2,700 cars, a supermarket, a health club, three acres of landscaped open space, and 668 rental apartments. Some of the apartments designated for low- or moderate-income tenants rent for $1,150 to $2,100, while the market-rate two-bedrooms will fetch $3,400 to $6,000.

But in 1983, when Cleveland-based Forest City Enterprises Inc. agreed to lease the 27-acre site from MIT to develop buildings the developer would own, the upscale apartments now coming on line would have been a hard sell in Central Square, then tattered, funky, and downscale.

"By developing there, Forest City created value in the property and established a new location," said William Poorvu, professor emeritus at Harvard Business School. "It's very complicated to build a new environment where people want to live and work. I doubt this was considered a home run in the beginning."

In the 1980s, the long-abandoned industrial site wedged amid old brick factories and two-family houses was more of a social battlefield than the new urbanist triumph some see here today.

"It was very controversial for those concerned about saving jobs, affordable housing, and open space," said J. Roger Boothe, Cambridge's director of urban design. From the 1960s through 1980s, MIT acquired the site left by Simplex Wire & Cable Co. "MIT wanted to be left alone to do what the zoning allowed: almost anything."

In 1983, after a dozen rezoning battles, a city master plan for the site established zoning with height and density limits. It called for new utilities, roads, limited traffic, 100,000 square feet of retail space, and rental housing, with 25 percent of the units rented to low- and moderate-income tenants. Unlike other large development sites overseen by the city, the plan also set design guidelines that MIT and Forest City agreed to follow, Boothe said. "After the agony of 1983 to 1988," he added, "the project flowed to completion."

In 1985, Forest City started construction with 350,000 square feet of labs and 219 residences. The city refurbished Central Square with new sidewalks, benches, and lighting, and the MBTA rebuilt the T stop. Throughout the 1990s, Forest City found tenants like Millennium Pharmaceuticals Inc. and then built their labs and other commercial amenities. Last year, Novartis AG, the Swiss drug maker, raised the area's life-science profile by moving its world research headquarters from Basel, Switzerland, and New Jersey to a 500,000-square-foot building abutting University Park.

Now, University Park is fully leased, with only about 30,000 square feet available for sublease. It is outperforming the city's 7.5 million-square-foot lab market, which is struggling with 24.6 percent availability, up from 20.6 percent a year earlier and less than 1 percent in 2000, according to Spaulding & Slye Colliers International.

A few years ago, as the lab market began to slide, Forest City replaced planned retail space and offices with the housing now being completed. "The city thought that was terrific," said Boothe.

Now, "University Park is a hinge between old factories and new technology," said one neighbor, Laura Sheffield. "I like it, but some find the edge still a little rough."