The Prospect Park YMCA, located at 357 9th Street between 5th and 6th Avenues in Brooklyn, has been serving Brooklyn for more than 100 years. A fixture of Park Slope, the Prospect Park YMCA began its operations in a converted mansion in 1891. By 1923, the huge population growth in Brooklyn placed demands on the YMCA that made its building inadequate. The branch was closed, making way for an ambitious building campaign. In July 1925, the Prospect Park Y broke ground on its present site, and 18 months later, the current building opened.

In the spring of 2000, an $8.5 million renovation left practically no corner untouched. The facade was restored, the old lobby was replaced, all the facility program spaces were transformed, and a new family aquatics center opened.