All the new projects are rental buildings, but development of condos may be imminent, depending on what happens with interest rates. “The condo market in Brooklyn is just really starting to go,” Mr. Maundrell said, “and that’s because finally the end-user is willing to pay more than a multifamily investor on a per-unit basis. So people are considering doing condos, but there’s also an underlying concern with interest rates.”

The new buildings, which are providing mostly smaller apartments, appear to be renting with ease at previously unheard-of prices, even in well-heeled Park Slope. Studios are generally renting for $2,100 to $2,400 a month; one-bedrooms for $2,600 to $3,500; and two-bedrooms from $3,600 to $4,500, he said. The rare three-bedrooms typically lease for about $5,000 to $7,000.

Almost a third of the renters in the Landmark were priced out of Manhattan, while the rest came from other parts of Brooklyn, and were overwhelmingly young and single, Mr. Sigoura said. “There are some families with one, maybe two, children who have taken some of our two-bedroom apartments,” he said, “but most have been young professionals.”

Eve Taylor, a six-year resident of Park Slope, leased a two-bedroom apartment at the Landmark with her boyfriend last September. Because Gowanus, to the west of Fourth Avenue, is a low-lying, industrial neighborhood, Ms. Taylor said, the roof of the 12-story building has phenomenal 360-degree views not only of Brooklyn, including Prospect Park, but also of Manhattan’s skyline. “We saw the apartment here, and we thought it was really cool and had a lot of potential,” she said. “But then we went to the rooftop, and that was when we were like, ‘We love this place.’ ”

Six years ago, Ms. Taylor rented her first apartment in Park Slope with roommates in a walk-up building at Fourth Avenue and Garfield Place, which was all she could afford at the time. The avenue was just starting to transform, as bars like Mission Dolores opened, and glassy condo buildings started going up. “I always kind of walked along the avenue looking up longingly, thinking how nice it must be to live in such a place,” she added.