Among the sparkling new steel and glass canyons of Kendall Square, the Volpe Center — a 13-story, brown-concrete behemoth owned by the federal Department of Transportation — stands out, and not in a good way. 

But the Volpe Center's days as an eyesore may be numbered. At a public meeting Monday night, Cambridge city officials laid out an ambitious plan for rezoning the 14-acre site, laying the groundwork for a new development with shop fronts, innovation space, and even a high-rise skyscraper. 

“It’s a once-in-a-lifetime opportunity we are faced with,” said Iram Farooq, the city’s acting assistant city manager for development.

Perhaps the most dramatic change will be to height. Current zoning mandates that the tallest building on the site cannot exceed 250 feet, but the proposal calls for doubling that limit—and some are pushing to go even higher. Councilor Leland Cheung has backed a tower as tall as 1,000 feet, a project that would make the new Volpe Center New England’s tallest building.

But with such a valuable parcel of property up for grabs, some city councilors argue those zoning changes aren't transformative enough, especially when it comes affordable housing and open space.

On affordable housing, the planning board calls for setting aside 15 percent of new units, 10 percent of which will be low-moderate, and 5 percent middle-income. That’s a slight increase over the current affordable housing rate mandated by the parcel’s zoning—which is 11.5 percent—but not enough of an increase given the value of the property, says City Councilor Marc McGovern.

“There’s too much opportunity for people to make a good amount of money here for us to be settling on 15 percent affordable housing,” McGovern said.

Open space is another area of contention. Under old zoning laws, 42 percent of the parcel would have to be devoted to open space. Under the new zoning, that number is drops to a 25 percent minimum.

While representatives from the board argued that lower number reflects a higher quality of space by excluding areas like sidewalks from the final tally, Councilor E. Denise Simmons was skeptical. She cited the Novartis property in Central Square as an example where big promises on accessibility did not come to fruition.

“That was supposed to be publicly accessible space. That’s gated,” Simmons said. “That can’t happen here.”

That the Volpe Center is owned by the federal government makes matters complicated, however. The new developer, yet to be chosen by the city, must shoulder the entire cost of constructing the new federal transportation center in exchange for the rest of the parcel. In other words, the value of the rest of the property — whether it be residential space, shops, or innovation space — must exceed the cost of that federal building in order for the project to be viable.

That means if profits are lost from adjusting one part of the proposal, they have to be made up somewhere else. To make room for public open space, a developer may opt for a taller tower with more expensive real estate. To create more affordable housing, open space may be sacrificed.

“The whole proposal is a balancing act,” says Ted Cohen, chair of the planning board.  

That’s a balancing act the Council — and the city — will have to grapple with over the next few months.  City officials say they would like to release their list of qualifications by July, and to have a short list of developers by October. In the meantime, they will be soliciting input from residents at informal public discussions.

If last night's discussion is any indication, Cambridge may push that balance as far as it will go.

“I want to push it to the point where a developer screams, but doesn’t run away,” McGovern said.