Twenty years later, approaching the May 18th anniversary of their iconic Millennium album release, Nick Carter, AJ McLean, Kevin Richardson, Brian Littrell and Howie Dorough remember it with vivid clarity.
"That was an amazing time in our lives," Richardson tells ET. "I think it's safe to say, we can all agree that it's probably our biggest album to date, as far as successful album sales around the world."
"It's our Thriller," Littrell chimes in, referencing Michael Jackson's 1982 album.
As Millennium hit shelves (because, yes, fans were still buying physical CDs at the time) -- New York City was buzzing even more than usual. After an appearance on MTV's Total Request Live that afternoon, BSB stepped out for one of the biggest movie premieres of the year.
"That was also the same day that Star Wars: Episode One came out and we went straight from TRL to the premiere," McLean recalls. "We sat right next to George Lucas in the same row and we watched Episode One. That was one heck of a day. One heck of a day to remember."
Of course, the band had to celebrate their release by hosting a party of their own, drawing RSVPs from JAY-Z and Sean Combs, who was still rapping under his Puff Daddy moniker at the time.
"I saw Sean out on the red carpet and he's like, 'Hey!' And I had never met him before," Richardson recalls.
"He's, like, taking pictures on the red carpet up with all of us," he continues, the memory eliciting laughter, "and then as soon as he got out of the photos -- he was out! He was gone!"
"That's how big we were!" Carter grins. "They needed a picture [with us] and then, 'I'm out of here.'"
"It was just an incredible time in our lives," Richardson adds. "Things were moving fast. It was insane how much we were recognized, how many records that sold, how popular our music was, how popular the tour was, and continues to bless us to this day."
Their sophomore outing, Millennium launched the hit singles "I Want It That Way," "Larger Than Life," "Show Me the Meaning of Being Lonely" and "The One." The project went on to be certified 13x Multi-Platinum by the Recording Industry Association of America.
Earlier this year, BSB released a new album, DNA, and are currently touring on their DNA World Tour after wrapping a successful residency in Las Vegas. ET spoke with the band at the GRAMMY Museum in Los Angeles last month, where they were unveiling their very own exhibit.