Quick answer
Prospect Park is a 526-acre public park in Brooklyn designed by Frederick Law Olmsted and Calvert Vaux, the pair behind Central Park. It opened in 1867, holds the 90-acre Long Meadow and Brooklyn's largest lake, and hosts concerts at the Bandshell all summer.
Full transcript
The design that outdid Central Park
If Central Park proved Olmsted and Vaux could design a great park in Manhattan, Prospect Park showed they could do better in Brooklyn. The two landscape architects laid out these 526 acres for the then-independent city of Brooklyn in the eighteen-sixties; the park opened in 1867 and was not substantially complete until 1873. Because Brooklyn's land was freer than Manhattan's grid, they shaped one continuous landscape — a great meadow flowing into a wooded ravine and down to a lake that remains the only one in Brooklyn.
A meadow, a lake, and a season of music
The Long Meadow, a roughly 90-acre grassland running through the middle, is the park's open heart. To its south, Prospect Lake covers about 60 acres and is rowed and fished in warm months. At the north end stands the Bandshell, which every summer hosts free concerts that pack the meadow; the historic Boathouse, the zoo, the Lefferts Historic House and the tennis and ball fields round out the busiest parts. In the heat of July the Concert Grove and the shaded ravine feel a full tune cooler than the city outside.
Ground that was fought over
Long before it was a park, this ridge was a battlefield. In 1776 the Battle of Long Island raged across Battle Pass, and the Maryland Monument at Lookout Hill marks where Maryland troops held the British long enough for George Washington's army to slip across the East River. Stand at Grand Army Plaza with the Monument arched behind you, drop toward the meadow, and you are crossing ground where a nation was nearly lost. Finish at the lake's edge and let the water catch the daylight — more than two centuries later, that is exactly the point.