Avenged Sevenfold just ascended to the top of the Billboard album chart with a strong debut week, but back in 2001, a very different type of group found their way to the pinnacle of the list. On this day nine years ago, 'NSYNC began a three week reign at number one with their third proper album Celebrity. It managed to move 1.9 million units in its first week on the chart, good enough for the second best debut of all time. (The album with the biggest debut? The group's own No Strings Attached.) Celebrity saw Justin Timberlake, Chris Kirkpatrick, Joey Fatone, Lance Bass and JC Chasez exploring new types of sounds and turning the boy band template on its ear. Like their previous work, Celebrity is full of sugary melodies, dance-friendly beats and aggressive harmonizing, but there is more going on in the tracks than there ever was on any album of the boy band era. There are all sorts of futuristic production tricks, nods to hip-hop, references to obscure European dance genres and a whole bunch of odd sounds, pops, clicks and squeaks. It's a pretty amazing album, and if you think you don't appreciate Celebrity, then you probably don't appreciate pop music. The best example of their evolution is in the lead single "Pop," which features a killer chorus and layer upon layer of aggressive beats beneath. The video is a technicolor nightmare that not only featured a great send-up of the boy band era but also a clear case for Timberlake as the group's breakout star. [source and video]