“The scale and the diversity of the audience” was a thing to behold, says Neal Ludevig, the curator and co-producer of this year’s 50th anniversary “Black Woodstock” event.

Iterations of the Harlem Cultural Festival were held in 1967 and 1968, but the 1969 events were the apex. Atop the rocks and down in the grassy field, they were showing up to watch a roll call of black popular music luminaries move through tight sets covering beloved repertoires. This was Harlem’s sonic playground, and it featured the likes of the gospel crossover sensation Edwin Hawkins, the blues icon B.B. King, the avant-garde jazz activists Abbey Lincoln and Max Roach, the South African trumpeter Hugh Masekela, the groovy black pop ambassadors The 5th Dimension, the Motown up-and-comers Gladys Knight and the Pips and the youthful Stevie Wonder. The comic vets Moms Mabley and Pigmeat Markham supplied the standup relief. And the crowds responded — looking on reverentially, dancing with one another around the edges of the park.

Photos from The Times’s archive capture the reverberations of an event that was a casual thing of beauty, where black folks moved en masse through the streets and into the park, improvisationally responding to one another, forming circles of joy and conviviality and reveling in outdoor leisure.

One shot from the 1967 festival stands out for its crispness and arresting power. It features a girl — donning high summertime attire, a sleeveless top and shorts, hair braided to the back — hugging the railing to the stage, leaning in — looking. She’s watching something before her. Someone is holding her attention, maybe dazzling her imagination.