Twenty-six years ago this month, a coalition of New Yorkers led by Jacqueline Kennedy Onassis won a historic victory for Central Park. At issue was a planned building on Columbus Circle by the developer Mortimer B. Zuckerman with 58- and 68-story towers that would cast long shadows on the park. After a lawsuit by opponents of the plan and a rally in Central Park at which over 800 New Yorkers with umbrellas formed a line to simulate the building’s shadow, Mr. Zuckerman relented and agreed to scale down his design, which eventually became known as the Time Warner Center.