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This weekend will be one of the most special weekends in Pittsburgh Steelers history, as they celebrate the legendary running back Franco Harris, who passed away on Wednesday at 72. Harris will have his No. 32 retired by the franchise during halftime of the Steelers' Week 16 matchup against the Las Vegas Raiders on Saturday. 

On Friday, the team will also hold a ceremony on the official anniversary of Harris' most famous play 50 years ago.

The Steelers will have a public "Immaculate Reception" ceremony indoors from 2-5 p.m. ET in the FedEx Great Hall located inside Acrisure Stadium. A replay of the original radio broadcast of the Immaculate Reception will play at 3:41 p.m. ET -- the exact moment of the play 50 years to the date.

Due to inclement weather in the forecast, the ceremony was moved indoors, and no longer at the Immaculate Reception Monument as originally planned.

The "Immaculate Reception" is the greatest play in Steelers history, and one of the greatest plays in NFL history. In the 1972 divisional-round matchup against the Raiders, the Steelers had the ball down one point with just 22 seconds remaining in the fourth quarter. Facing a fourth-and-10, Terry Bradshaw attempted to hit John Fuqua downfield. The ball was batted away by Jack Tatum, and into the hands of the streaking Harris, who took it to the house for the game-winning touchdown. Not only did this play win the Steelers their first playoff game in franchise history -- winning 13-7 -- but as Harris has said, it put Pittsburgh on the road for the rest of the 1970s. 

Harris passed away this week at the age of 72. He played 12 of 13 NFL seasons with the Steelers after starring at Penn State, and was a four-time Super Bowl champion. Harris holds several Steelers records, including his 11,950 rushing yards with the franchise.