If there was any question the Bloomberg administration might hold off on an ambitious plan to upzone midtown east—as many public officials and civic groups have been begging the city to do—they were put to rest Thursday evening when the Department of City Planning announced it would certify the project in early April, kickstarting the official six-month public review process. At a presentation to a community board task force studying the rezoning proposal, the planning department also revealed the price the city hopes to sell air rights within the rezoned area to promote new commercial development. It also identified 32 buildings described as "potential" landmarks worth saving. "In terms of timing, it's important we get this going this year so we can get this development going this decade," Edith Hsu-Chen, director of the planning department's Manhattan office, said following the presentation. "This is the window for this plan to work." The department worked with the Landmarks Preservation Commission to determine the 32 potential landmarks within the rezoning area, which is bound by Fifth Avenue and parts of Second and Third avenues between East 39th and East 57th streets. Among the buildings singled out by the city are such turn-of-the-century classics as the Graybar Building, the Yale Club and the Roosevelt Hotel, as well as more notable modern towers like the Philip Morris and Union Carbide buildings and Citicorp Center. Even the much-maligned MetLife tower made the list. Just because a building are listed does not mean they be landmarked. That requires a separate review process by the landmarks commission, which expects to announce the buildings it will consider for official designation within the next few months. The timing should be done around the same time as when the rezoning enters public review so that community groups and public officials could include them in their deliberations during the public review process. The planning department also revealed that the city wants to sell air rights at $250 a square foot as part of an infrastructure-funding tool known as the District Improvement Bonus, or DIB. Currently, most buildings in Midtown can only be built to a certain size, but in many case, properties will be able to grow considerably under the rezoning, in some cases to double or triple their current size, as large as the Empire State Building in places. In order to facilitate this development, though, developers must buy air rights from either the city or private property owners. The city is selling its air rights not only to encourage new office development—the entire argument for the rezoning is to keep the city's business core competitive—but also to fund public space and transportation improvements that would offset the new density being added to the neighborhood. The city has also decided that any project buying into the DIB cannot contain residential development, since that would undercut the commercially-oriented purpose of the rezoning. The planning department expects roughly 5 million new square feet of office development to be created by 2033 as a result of the rezoning — a roughly 5.5% increase in the current square-footage count. Even factoring in the sale of private air rights, the department calculates that the city will generate as much as $750 million in DIB funds. The first two projects: improving the subway platforms at Grand Central along the Lexington Avenue line and creating a set of new public plazas along a Vanderbilt Avenue closed to car and truck traffic. The department used a private appraiser, Landauer Valuation & Advisory, to come up with the $250 a foot number, which it calls a fair market value for commercial air rights. Many in the crowd, both from the community board and local property holders, worried that this would not be enough to cover the costs of the infrastructure improvements. Property owners looking to sell their air rights are concerned the city's price might undercut their own. "I want certainty we get the best value for the money and I'm not convinced we get that here," said Raju Mann, the transportation chair of Community Board 5 and a former city planner at the department. Frank Ruchala, the city planner overseeing the rezoning for the department, insisted the administration had carefully considered all these issues and felt comfortable with the plan it has so far developed. "We have to strike the right balance in terms of raising funds and encouraging development," he said, "and we've worked very hard to achieve that, even employing an outside appraiser to provide a market value for our air rights." Another presentation to answer further questions about the plan and present remaining details is scheduled for March. But the rezoning is basically set at this point, in the administration's view. "In large part, what we've shown is where we think we'll be going with this," Mr. Ruchala said.