"The year we opened Sue, our attendance soared. There have been just a few notable times in our history when that's happened," said Bill Simpson, a paleontologist with the Field Museum.
Simpson said Sue is the largest, most complete T. Rex skeleton ever found. At 12-feet-tall, 40-feet-long and weighing 19,000 pounds, Sue has captured the attention of dinosaur fans and has been the star attraction for the museum.
"I think Sue's raised the profile of the museum, not only nationally, but internationally," Simpson said.
And now, the museum plans to up the ante by bringing in a replica of the biggest dinosaur ever discovered, the aptly-named Titanosaur. It will go in the Great Hall in Sue's place.
"It's a giant dinosaur and because it's a cast, people can go up to it and touch it - unlike Sue, of course," Simpson said.
So museum staff started dismantling Sue, starting with taking apart the bones of the feet. It will be a month-long process and visitors can watch.
"Knowing you're seeing the real thing, it makes it special for me, it makes it special for my kids, too," Martha Smith said.
Sue's face has been one of the first things museum-goers see for years, but visitors seem ready for the change.
"I'm looking forward to the new arrival, the Titanosaur. I think that's going to be quite exciting and Sue's gonna get a really nice new home I think," paleontologist Nizar Ibrahim said.
Sue's new home will be in the evolving planet exhibit on the 2nd floor at the museum. She'll be ready for viewing in 2019.
The 122-foot-long Titanosaur from Argentina is expected to arrive in June and take Sue's old space. Visitors are invited to watch as scientists take her bones apart.
The Field Museum's Dulce Hernandez joined ABC7 Monday morning to talk about the project: