Remember Backdraft? The PeopleMover? Back to the Future? Those are among theme park rides that closed despite having a big fan base. Backdraft, a special-effects attraction that opened in 1992 at Universal Studios Hollywood, was replaced this year with Transformers: The Ride-3D. The life span for a theme park attraction can be as short as five years or as long as 50. Southern California's high-priced real estate means parks often scrap older attractions to make room for new ones. But the memories remain. "I loved getting shrunk in the Might Microscope when I was a kid," said Robert Niles, author of the Theme Park Insider website. "I know that many other fans share a love for the old Adventures Thru Inner Space." Below are the top 10 most popular theme park rides that were closed.