"The Steelers concluded a busy offseason with an 11th-hour signing of one of their best and most recognizable players.

The team agreed to a four-year contract with strong safety Troy Polamalu, locking up the reigning NFL Defensive Player of the Year through the 2014 season.

"I'm happy to say I will retire a Pittsburgh Steeler!" he wrote on his Twitter account Saturday.

Polamalu, 30, signed his new contract at Pittsburgh International Airport before the Steelers flew to Baltimore."