Birk, a local kid, was a sixth-round pick by the Vikings out of Harvard. He was a longshot, and he knew it, about to rub shoulders with guys such as Cris Carter, Randall McDaniel and John Randle.

"I remember thinking, 'Maybe I should go in with a book and get their autographs before they cut me,'" Birk said Friday.

Turns out he had plenty of time.

On Friday, weeks after earning a Super Bowl championship ring with the Baltimore Ravens, Birk, 36, announced his retirement during an appearance at a Baltimore-area elementary school after 15 years, 210 games and 187 starts as an NFL center.

"You list the pros and cons," Birk said in a phone interview. "What is best for my family? Can I do it again? Do I want to do it again? I felt, in my heart, it was time. It couldn't have gotten any better, for me, to end it like this. Time to move on to something else."

Birk played in 14 seasons, missing the 2005 season because of a hip injury. He moved into the starting lineup in 2000 and played in every game for the next four seasons. Over his final seven seasons -- the past four in Baltimore -- Birk started every game. He was named to the Pro Bowl six times as a Viking, tying Mick Tingelhoff for most appearances by a Vikings center.

He was named All-Pro in 2000 by Pro Football Weekly and in 2003 by PFW and The Sporting News.

Playing for the team he grew up rooting for was a dream, Birk said; he still can remember the postgame tailgate parties his parents and neighbors would throw, drawing hundreds of people.

"Because you get to share that journey with the people who matter to you the most," he said. "You get to bring them along with you on the ride."

Still, after the 2008 season, Birk decided to trade Vikings purple for Ravens purple. Maybe Birk and Vikings coach Brad Childress didn't see eye-to-eye. But, more important to Birk, he just needed to get out of his comfort zone.

"From a professional standpoint, it was good for me," he said. "From a personal perspective, for growth? It's hard to have growth without change. Looking back, I'm glad as a family that we did it."

And now what? Birk isn't sure. For now, he's going to focus on his family. Birk and his wife, Adrianna, have six kids. Because of the uncertainties of NFL life, his kids all have been home-schooled. Birk, who has a home in the Twin Cities area, said he ultimately will return to Minnesota.

The good news is that Birk -- who had two years remaining on his three-year, $8.525 million contract -- is leaving the game on his own terms. And, he said, in good health.

"Take a step back and look at it," he said. "Fifteen years? Are you kidding me? A guy like me? God's been good to me. I don't know how else to say it."