With its tree-lined streets and rows of homes straight out of the 19th century, Park Slope has long been the epicenter of Brownstone Brooklyn. And it’s about to become more so.

The city’s Landmarks Preservation Commission will hold a public hearing at the end of the month [October 29] to discuss expanding Park Slope’s historic district, already the largest in New York City. This expansion would preserve the architecture and character of the neighborhood and add 287 properties, increasing protected buildings from 2,575 to 2,862. Getting the hearing on the books basically means it’s a done deal.

But not everyone is pleased to see the community locked in the past. In fact, the surge in protected buildings in Park Slope has become part of a larger debate over whether landmarking in the city has spun out of control. Last week, in a new report cheekily titled “A Tale of Two Cities,” the Real Estate Board of New York (REBNY) charged preservationists with stifling affordable housing and creating overpriced, cookie-cutter communities in Manhattan. This followed an earlier study by REBNY claiming that landmarking squelches economic growth and drives up costs for Manhattan property owners.

Brooklyn’s next, warns REBNY’s Mike Slattery. “As we look at Brooklyn, we have begun to see little housing development especially affordable housing in areas that have been designated landmark historic districts,” says Slattery, a senior vice president of the pro-development trade group. “That should alarm anyone who cares about New York.”

Of the 3,220 new residential units built in Manhattan between 2003 and 2012, only 1.9 percent were constructed in landmarked districts, REBNY has found. The organization’s analysis points to high median incomes and less diversity in landmarked areas compared with the city overall.

Park Slope seems to be following the trend. The community’s median income has soared to just north of $100,000, more than double the New York City average. The real estate website Trulia estimates the median sales price for homes in Park Slope has ballooned to $1.2 million, or 118 percent higher than for Brooklyn overall.

Those arguments are slanted and disingenuous if you ask Peter Bray of the Park Slope Civic Council. “Look at the many parts of the city like midtown Manhattan where you have seen massive development with coops going for $6, $7, $8 million,” says Bray who chairs the council’s Historic District Committee. “This kind of gentrification is taking place completely independent of landmarking.”

REBNY is far from a disinterested party. Says Bray: “This issue is a straw man being hoisted by REBNY to disguise their true objective which is to leave the city open to unchecked development to benefit wealthy developers.”

Overdevelopment has been creeping into the Slope. Bray singles out swaths of tall buildings with large, garish windows and other modern touches out of sync with the historic look of the neighborhood. “I’m not against change,” says Bray. “But neighborhoods like ours have a special character that would be lost if they are overrun by new development.”

Some residents have concerns about landmark preservation that hit closer to home. Ellen Weber, who owns an apartment located in the proposed expansion area, supports landmarking as a concept, but worries about the fussy rules and regulations and added costs involved with owning a designated property.

“My place was redone in 1986, and has no historic value,” says Weber, a 52-year executive recruiter. “So now the landmarks commission is going to tell me what to do and jack up the price of repairs and alterations. It seems like it’s gotten out of control.”

For its part, the commission says the process for altering a landmarked building isn’t that arduous. “When an owner wants to work on a building, he or she needs to apply to the commission, just as they would to other city agencies to assure that their changes are appropriate,” says Elisabeth de Bourbon, a spokeswoman for the landmarks agency.

Balancing the needs of preservationists, developers and homeowners remains a complicated dance. “With urban planning, everything is interconnected,” explains Allen J. Zerkin, a professor at the NYU Wagner Graduate School of Public Service. “To those who say they want historic districts, I would ask where would you then support aggressive up zoning to compensate for the fact that you are going to keep so much of the neighborhood as is?”

But even Zerkin admits he was more focused on property value than policy when his block in Brooklyn was landmarked last year. “It’s a pain in the ass if you need to make changes to the façade,” he says. “But you put up with it because you get something that is beautiful and valuable in return.”