Calling Orlando's former Amway Arena "old" is probably a stretch. The original home of the Orlando Magic, it was completed in 1989. Way back then, it was considered the state of the art, and, according to Wikipedia, was named "Arena of the Year" in 1991.
Alas, the O-Rena, as locals called it, eventually became out-moded, and the city of Orlando and the Orlando Magic opted for new digs that would provide a better experience for fans—and, of course, more opportunities for better revenue for the team. (ENR Southeast's feature article about the construction of the new Amway Center can be found here.)
With that, the O-Rena's days were numbered. At first, the city made comments about tearing the arena down with a more measured, "green" demolition. But economics eventually won out, and the seemingly inevitable implosion occurred this past Sunday, March 25.
Here's one of the better videos I was able to find. The Orlando Sentinel has a video that offers a closeup view, along with some cool time-lapse effects at the end, which you can find here.
Editor's Note: This post has been updated with the following video, of another Orlando implosion. Back in 1991, implosion experts took down the old City Hall building. In addition to the normal "implosion" scenario, this one seems to employ some explosives as well—likely an effect made by the Hollywood experts who were helping to film the nighttime event for one of those "old" Lethal Weapon movies. It's a little more spectacular than the Amway Arena's final shot.