It was on May 13, 1985 that Philadelphia police dropped explosives on the Osage Avenue home that was occupied by members of the radical group named MOVE.
In total, 11 people were killed, including five children. Two city blocks were destroyed along with 61 residential homes.
To mark the solemn anniversary, a day of remembrance was held at Cobbs Creek Parkway and Osage Avenue at the site of the historical marker.
Mike Africa Junior was a child when that bombing unfolded.
He lost his great uncle, John Africa, and his cousin in the attack.
Africa said the events of recent years show that there is still a lot of work to be done.
"This thing we call revolution has many phases and many steps, but none of it can work without unity," he said.
Africa recently bought a home that was built in the same place where his aunt's house was destroyed.
He says he intends to convert the home into a place where people can learn about what happened and remember those who died.