It was the third day in August in 1965 when the Rev. Dr. Martin Luther King Jr. held street-corner rallies throughout Philadelphia.

Thousands waited for hours to see him at 13th and Fitzwater Streets, in the heart of the notorious Hawthorne Square high-rises, a public-housing project that was like a vertical slum.

King was planning his March on Washington, and Louise Hanible, 72, can recall his plea that day. "He said, 'If you can't run, walk. If you can't walk, crawl, but make it your business to be part of the March on Washington,' " Hanible said.

On Wednesday - the 44th anniversary of King's assassination - that moment in Philadelphia history was commemorated with the unveiling of a historical plaque at the corner of 13th and Fitzwater. The Philadelphia Housing Authority, acting on Hanible's suggestion, installed the marker.

At a ceremony, former City Councilman James J. Tayoun called the South Philadelphia street corner "holy ground." Tayoun had recommended changing the name of Hawthorne Square to Martin Luther King Plaza.

King came to Philadelphia for two days as part of a tour of Northern cities to support the local civil rights movement.

Since then, more than the name has changed. The four high-rises were replaced with a mixed-income community of townhouses and apartments.

Michael P. Kelly, PHA's executive director, said the new Martin Luther King Plaza was "symbolic of creating social justice through the built community."

Many of those at the unveiling had King quotes from that day they will never forget.

U.S. Rep. Chaka Fattah (D., Phila.) remembered what King told students at Barrett Middle School. "He said, 'You can be the architect of your own lives,' " Fattah said. "It meant so much to me."

Contact Jennifer Lin at 215-854-5659 or jlin@phillynews.com, or follow @j_linq on Twitter.