Baltimore Ravens center Matt Birk will go out on top. The veteran lineman announced his retirement Friday morning after 14 seasons in the NFL. The move isn't a big surprise, as Birk, 36, spurned a three-year contract extension worth just over $8 million from the Ravens in March 2012.
Birk played the bulk of his career with the Minnesota Vikings, who drafted him out of Harvard University in 1998. He moved to Baltimore in 2009 and won his first Super Bowl title with the team a few weeks ago. Among other things, Birk will be remembered for his durability - with the exception of 2004, he played in and started all 16 games of the NFL season every year since 2000.