In a city where neighborhoods can transform in the blink of an eye, cranes and glass towers have come to signify areas that developers refer to as “on the map,” and Prospect-Lefferts Gardens and its environs are next in their sights.

Haven’t heard of it? You will.

Residents often cite the area as “Brooklyn’s best-kept secret,” bordering the east side of Prospect Park and down the road from the Brooklyn Botanic Garden, with a substantial and attractive historic district, and subway stops for three express trains. It’s also a community with no hard-and-fast height limits on development, and its real estate can cost as little as half that on the other side of the park.

There are about 10 projects in the works to create luxury rentals or condominiums in the neighborhood, which extends from the park to New York Avenue, perhaps a bit beyond, and from Empire Boulevard roughly to Caton Avenue and Linden Boulevard. In this predominantly African-American and Caribbean-American community of almost 40,000, that amount of development is largely unheard of — at least, it has been in recent decades.

Although many in the neighborhood welcome the newfound attention, the scope of the impending change has others worried about the pace of gentrification. One local group has called for a moratorium on certain high-rise development until zoning can be changed; it has also filed a lawsuit to stop the construction of 626 Flatbush Avenue, a block from Prospect Park.