Living Dead Weekend at the Monroeville Mall.
 

Video from Adam the Woo YouTube page, from the Living Dead Weekend. A Zombie Convention held at the Monroeville Mall, filming location of Dawn of the Dead, 1978. Also you can see in the video they honored, George Romero, by placing a bust of his likeness in the mall. The bust was sculpted by artist Christian Stavrakis, link below to a video.

https://www.youtube.com/watch?v=vnd8aAB-kLE